2138 lines
89 KiB
HTML
2138 lines
89 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
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"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
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<head>
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<meta http-equiv="Content-Type" content="application/xhtml+xml; charset=UTF-8" />
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<meta name="generator" content="AsciiDoc 8.6.8" />
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<title>Cpuset (cset) Tutorial</title>
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<style type="text/css">
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/* Shared CSS for AsciiDoc xhtml11 and html5 backends */
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/* Default font. */
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body {
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font-family: Georgia,serif;
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}
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/* Title font. */
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h1, h2, h3, h4, h5, h6,
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div.title, caption.title,
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thead, p.table.header,
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#toctitle,
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#author, #revnumber, #revdate, #revremark,
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#footer {
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font-family: Arial,Helvetica,sans-serif;
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}
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body {
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margin: 1em 5% 1em 5%;
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}
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a {
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color: blue;
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text-decoration: underline;
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}
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a:visited {
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color: fuchsia;
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}
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em {
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font-style: italic;
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color: navy;
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}
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strong {
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font-weight: bold;
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color: #083194;
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}
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h1, h2, h3, h4, h5, h6 {
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color: #527bbd;
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margin-top: 1.2em;
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margin-bottom: 0.5em;
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line-height: 1.3;
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}
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h1, h2, h3 {
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border-bottom: 2px solid silver;
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}
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h2 {
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padding-top: 0.5em;
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}
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h3 {
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float: left;
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}
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h3 + * {
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clear: left;
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}
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h5 {
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font-size: 1.0em;
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}
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div.sectionbody {
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margin-left: 0;
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}
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hr {
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border: 1px solid silver;
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}
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p {
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margin-top: 0.5em;
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margin-bottom: 0.5em;
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}
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ul, ol, li > p {
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margin-top: 0;
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}
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ul > li { color: #aaa; }
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ul > li > * { color: black; }
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.monospaced, code, pre {
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font-family: "Courier New", Courier, monospace;
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font-size: inherit;
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color: navy;
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padding: 0;
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margin: 0;
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}
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#author {
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color: #527bbd;
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font-weight: bold;
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font-size: 1.1em;
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}
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#email {
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}
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#revnumber, #revdate, #revremark {
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}
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#footer {
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font-size: small;
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border-top: 2px solid silver;
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padding-top: 0.5em;
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margin-top: 4.0em;
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}
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#footer-text {
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float: left;
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padding-bottom: 0.5em;
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}
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#footer-badges {
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float: right;
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padding-bottom: 0.5em;
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}
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#preamble {
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margin-top: 1.5em;
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margin-bottom: 1.5em;
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}
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div.imageblock, div.exampleblock, div.verseblock,
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div.quoteblock, div.literalblock, div.listingblock, div.sidebarblock,
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div.admonitionblock {
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margin-top: 1.0em;
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margin-bottom: 1.5em;
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}
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div.admonitionblock {
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margin-top: 2.0em;
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margin-bottom: 2.0em;
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margin-right: 10%;
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color: #606060;
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}
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div.content { /* Block element content. */
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padding: 0;
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}
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/* Block element titles. */
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div.title, caption.title {
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color: #527bbd;
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font-weight: bold;
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text-align: left;
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margin-top: 1.0em;
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margin-bottom: 0.5em;
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}
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div.title + * {
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margin-top: 0;
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}
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td div.title:first-child {
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margin-top: 0.0em;
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}
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div.content div.title:first-child {
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margin-top: 0.0em;
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}
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div.content + div.title {
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margin-top: 0.0em;
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}
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div.sidebarblock > div.content {
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background: #ffffee;
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border: 1px solid #dddddd;
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border-left: 4px solid #f0f0f0;
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padding: 0.5em;
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}
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div.listingblock > div.content {
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border: 1px solid #dddddd;
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border-left: 5px solid #f0f0f0;
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background: #f8f8f8;
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padding: 0.5em;
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}
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div.quoteblock, div.verseblock {
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padding-left: 1.0em;
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margin-left: 1.0em;
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margin-right: 10%;
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border-left: 5px solid #f0f0f0;
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color: #888;
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}
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div.quoteblock > div.attribution {
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padding-top: 0.5em;
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text-align: right;
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}
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div.verseblock > pre.content {
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font-family: inherit;
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font-size: inherit;
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}
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div.verseblock > div.attribution {
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padding-top: 0.75em;
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text-align: left;
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}
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/* DEPRECATED: Pre version 8.2.7 verse style literal block. */
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div.verseblock + div.attribution {
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text-align: left;
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}
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div.admonitionblock .icon {
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vertical-align: top;
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font-size: 1.1em;
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font-weight: bold;
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text-decoration: underline;
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color: #527bbd;
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padding-right: 0.5em;
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}
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div.admonitionblock td.content {
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padding-left: 0.5em;
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border-left: 3px solid #dddddd;
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}
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div.exampleblock > div.content {
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border-left: 3px solid #dddddd;
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padding-left: 0.5em;
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}
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div.imageblock div.content { padding-left: 0; }
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span.image img { border-style: none; }
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a.image:visited { color: white; }
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dl {
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margin-top: 0.8em;
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margin-bottom: 0.8em;
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}
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dt {
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margin-top: 0.5em;
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margin-bottom: 0;
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font-style: normal;
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color: navy;
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}
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dd > *:first-child {
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margin-top: 0.1em;
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}
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ul, ol {
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list-style-position: outside;
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}
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ol.arabic {
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list-style-type: decimal;
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}
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ol.loweralpha {
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list-style-type: lower-alpha;
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}
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ol.upperalpha {
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list-style-type: upper-alpha;
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}
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ol.lowerroman {
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list-style-type: lower-roman;
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}
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ol.upperroman {
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list-style-type: upper-roman;
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}
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div.compact ul, div.compact ol,
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div.compact p, div.compact p,
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div.compact div, div.compact div {
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margin-top: 0.1em;
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margin-bottom: 0.1em;
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}
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tfoot {
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font-weight: bold;
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}
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td > div.verse {
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white-space: pre;
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}
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div.hdlist {
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margin-top: 0.8em;
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margin-bottom: 0.8em;
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}
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div.hdlist tr {
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padding-bottom: 15px;
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}
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dt.hdlist1.strong, td.hdlist1.strong {
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font-weight: bold;
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}
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td.hdlist1 {
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vertical-align: top;
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font-style: normal;
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padding-right: 0.8em;
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color: navy;
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}
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td.hdlist2 {
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vertical-align: top;
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}
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div.hdlist.compact tr {
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margin: 0;
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padding-bottom: 0;
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}
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.comment {
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background: yellow;
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}
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.footnote, .footnoteref {
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font-size: 0.8em;
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}
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span.footnote, span.footnoteref {
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vertical-align: super;
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}
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#footnotes {
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margin: 20px 0 20px 0;
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padding: 7px 0 0 0;
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}
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#footnotes div.footnote {
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margin: 0 0 5px 0;
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}
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#footnotes hr {
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border: none;
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border-top: 1px solid silver;
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height: 1px;
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text-align: left;
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margin-left: 0;
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width: 20%;
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min-width: 100px;
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}
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div.colist td {
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padding-right: 0.5em;
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padding-bottom: 0.3em;
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vertical-align: top;
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}
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div.colist td img {
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margin-top: 0.3em;
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}
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@media print {
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#footer-badges { display: none; }
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}
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#toc {
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margin-bottom: 2.5em;
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}
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#toctitle {
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color: #527bbd;
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font-size: 1.1em;
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font-weight: bold;
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margin-top: 1.0em;
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margin-bottom: 0.1em;
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}
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div.toclevel0, div.toclevel1, div.toclevel2, div.toclevel3, div.toclevel4 {
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margin-top: 0;
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margin-bottom: 0;
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}
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div.toclevel2 {
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margin-left: 2em;
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font-size: 0.9em;
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}
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div.toclevel3 {
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margin-left: 4em;
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font-size: 0.9em;
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}
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div.toclevel4 {
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margin-left: 6em;
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font-size: 0.9em;
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}
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span.aqua { color: aqua; }
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span.black { color: black; }
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span.blue { color: blue; }
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span.fuchsia { color: fuchsia; }
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span.gray { color: gray; }
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span.green { color: green; }
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span.lime { color: lime; }
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span.maroon { color: maroon; }
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span.navy { color: navy; }
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span.olive { color: olive; }
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span.purple { color: purple; }
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span.red { color: red; }
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span.silver { color: silver; }
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span.teal { color: teal; }
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span.white { color: white; }
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span.yellow { color: yellow; }
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span.aqua-background { background: aqua; }
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span.black-background { background: black; }
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span.blue-background { background: blue; }
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span.fuchsia-background { background: fuchsia; }
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span.gray-background { background: gray; }
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span.green-background { background: green; }
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span.lime-background { background: lime; }
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span.maroon-background { background: maroon; }
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span.navy-background { background: navy; }
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span.olive-background { background: olive; }
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span.purple-background { background: purple; }
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span.red-background { background: red; }
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span.silver-background { background: silver; }
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span.teal-background { background: teal; }
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span.white-background { background: white; }
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span.yellow-background { background: yellow; }
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span.big { font-size: 2em; }
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span.small { font-size: 0.6em; }
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span.underline { text-decoration: underline; }
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span.overline { text-decoration: overline; }
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span.line-through { text-decoration: line-through; }
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div.unbreakable { page-break-inside: avoid; }
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/*
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* xhtml11 specific
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*
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* */
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div.tableblock {
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margin-top: 1.0em;
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margin-bottom: 1.5em;
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}
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div.tableblock > table {
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border: 3px solid #527bbd;
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}
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thead, p.table.header {
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font-weight: bold;
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color: #527bbd;
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}
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p.table {
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margin-top: 0;
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}
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/* Because the table frame attribute is overriden by CSS in most browsers. */
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div.tableblock > table[frame="void"] {
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border-style: none;
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}
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div.tableblock > table[frame="hsides"] {
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border-left-style: none;
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border-right-style: none;
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}
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div.tableblock > table[frame="vsides"] {
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border-top-style: none;
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border-bottom-style: none;
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}
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/*
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* html5 specific
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*
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* */
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table.tableblock {
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margin-top: 1.0em;
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margin-bottom: 1.5em;
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}
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thead, p.tableblock.header {
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font-weight: bold;
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color: #527bbd;
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}
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p.tableblock {
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margin-top: 0;
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}
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table.tableblock {
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border-width: 3px;
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border-spacing: 0px;
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border-style: solid;
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border-color: #527bbd;
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border-collapse: collapse;
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}
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th.tableblock, td.tableblock {
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border-width: 1px;
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padding: 4px;
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border-style: solid;
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border-color: #527bbd;
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}
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table.tableblock.frame-topbot {
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border-left-style: hidden;
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border-right-style: hidden;
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}
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table.tableblock.frame-sides {
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border-top-style: hidden;
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border-bottom-style: hidden;
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}
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table.tableblock.frame-none {
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border-style: hidden;
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}
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th.tableblock.halign-left, td.tableblock.halign-left {
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text-align: left;
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}
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th.tableblock.halign-center, td.tableblock.halign-center {
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text-align: center;
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}
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th.tableblock.halign-right, td.tableblock.halign-right {
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text-align: right;
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}
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th.tableblock.valign-top, td.tableblock.valign-top {
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vertical-align: top;
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}
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th.tableblock.valign-middle, td.tableblock.valign-middle {
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vertical-align: middle;
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}
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th.tableblock.valign-bottom, td.tableblock.valign-bottom {
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vertical-align: bottom;
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}
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|
|
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/*
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* manpage specific
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|
*
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* */
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body.manpage h1 {
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padding-top: 0.5em;
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padding-bottom: 0.5em;
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border-top: 2px solid silver;
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border-bottom: 2px solid silver;
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}
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body.manpage h2 {
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border-style: none;
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}
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body.manpage div.sectionbody {
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margin-left: 3em;
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}
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@media print {
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body.manpage div#toc { display: none; }
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}
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|
|
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</style>
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<script type="text/javascript">
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/*<+'])');
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// Function that scans the DOM tree for header elements (the DOM2
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|
// nodeIterator API would be a better technique but not supported by all
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// browsers).
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|
var iterate = function (el) {
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for (var i = el.firstChild; i != null; i = i.nextSibling) {
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if (i.nodeType == 1 /* Node.ELEMENT_NODE */) {
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|
var mo = re.exec(i.tagName);
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if (mo && (i.getAttribute("class") || i.getAttribute("className")) != "float") {
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result[result.length] = new TocEntry(i, getText(i), mo[1]-1);
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}
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iterate(i);
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}
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|
}
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|
}
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|
iterate(el);
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return result;
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}
|
|
|
|
var toc = document.getElementById("toc");
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if (!toc) {
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return;
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}
|
|
|
|
// Delete existing TOC entries in case we're reloading the TOC.
|
|
var tocEntriesToRemove = [];
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var i;
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for (i = 0; i < toc.childNodes.length; i++) {
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var entry = toc.childNodes[i];
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if (entry.nodeName.toLowerCase() == 'div'
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&& entry.getAttribute("class")
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&& entry.getAttribute("class").match(/^toclevel/))
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tocEntriesToRemove.push(entry);
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}
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|
for (i = 0; i < tocEntriesToRemove.length; i++) {
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toc.removeChild(tocEntriesToRemove[i]);
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}
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|
|
|
// Rebuild TOC entries.
|
|
var entries = tocEntries(document.getElementById("content"), toclevels);
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|
for (var i = 0; i < entries.length; ++i) {
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var entry = entries[i];
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|
if (entry.element.id == "")
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entry.element.id = "_toc_" + i;
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|
var a = document.createElement("a");
|
|
a.href = "#" + entry.element.id;
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|
a.appendChild(document.createTextNode(entry.text));
|
|
var div = document.createElement("div");
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</head>
|
|
<body class="article">
|
|
<div id="header">
|
|
<h1>Cpuset (cset) Tutorial</h1>
|
|
<div id="toc">
|
|
<div id="toctitle">Table of Contents</div>
|
|
<noscript><p><b>JavaScript must be enabled in your browser to display the table of contents.</b></p></noscript>
|
|
</div>
|
|
</div>
|
|
<div id="content">
|
|
<div id="preamble">
|
|
<div class="sectionbody">
|
|
<div class="paragraph"><p>Alex Tsariounov <<a href="mailto:alext@novell.com">alext@novell.com</a>><br />
|
|
Copyright (c) 2009-2011 Novell Inc., cset v1.5.6<br />
|
|
Verbatim copying and distribution of this entire article are permitted
|
|
worldwide, without royalty, in any medium, provided this notice is preserved.</p></div>
|
|
<div class="paragraph"><p>This tutorial describes basic and advanced usage of the <strong>cset</strong> command to
|
|
manipulate cpusets on a Linux system. See also the manpages that come with
|
|
the <strong>cset</strong> command: cset(1), cset-shield(1), cset-set(1), and cset-proc(1) for
|
|
more details. Additionally, the <strong>cset</strong> command has online help.</p></div>
|
|
</div>
|
|
</div>
|
|
<div class="sect1">
|
|
<h2 id="_introduction">1. Introduction</h2>
|
|
<div class="sectionbody">
|
|
<div class="paragraph"><p>In the Linux kernel, the cpuset facility provides a mechanism for creating
|
|
logical entities called "cpusets" that encompass definitions of CPUs and NUMA
|
|
Memory Nodes (if NUMA is available). Cpusets constrain the CPU and Memory
|
|
placement of a task to only the resources defined within that cpuset. These
|
|
cpusets can then be arranged into a nested hierarchy visible in the "cpuset"
|
|
virtual filesystem. Sets of tasks can be assigned to these cpusets to
|
|
constrain the resources that they use. The tasks can be moved from one cpuset
|
|
to another to utilize other resources defined in those other cpusets.</p></div>
|
|
<div class="paragraph"><p>The <strong>cset</strong> command is a Python application that provides a command line front
|
|
end for the Linux cpusets functionality. Working with cpusets directly can be
|
|
confusing and slightly complex. The <strong>cset</strong> tool hides that complexity behind
|
|
an easy-to-use command line interface.</p></div>
|
|
<div class="paragraph"><p>There are two distinct use cases for <strong>cset</strong>: the basic shielding use case and
|
|
the "advanced" case of using raw <code>set</code> and <code>proc</code> subcommands. The basic
|
|
shielding function is accessed with the <code>shield</code> subcommand and described in
|
|
the next section. Using the raw <code>set</code> and <code>proc</code> subcommands allows one to
|
|
set up arbitrarily complex cpusets and is described in the later sections.</p></div>
|
|
<div class="paragraph"><p>Note that in general, one either uses the <code>shield</code> subcommand <em>or</em> a
|
|
combination of the <code>set</code> and <code>proc</code> subcommands. One rarely, if ever, uses
|
|
all of these subcommands together. Doing so will likely become too
|
|
confusing. Additionally, the <code>shield</code> subcommand sets up its required cpusets
|
|
with exclusively marked CPUs. This can interfere with your cpuset
|
|
strategy. If you find that you need more functionality for your strategy than
|
|
<code>shield</code> provides, go ahead and transition to using <code>set</code> and <code>proc</code>
|
|
exclusively. It is straightforward to implement what <code>shield</code> does with a few
|
|
extra <code>set</code> and <code>proc</code> subcommands.</p></div>
|
|
<div class="sect2">
|
|
<h3 id="_obtaining_online_help">1.1. Obtaining Online Help</h3>
|
|
<div class="dlist"><dl>
|
|
<dt class="hdlist1">
|
|
For a full list of <strong>cset</strong> subcommands
|
|
</dt>
|
|
<dd>
|
|
<p>
|
|
<code># cset help</code>
|
|
</p>
|
|
</dd>
|
|
<dt class="hdlist1">
|
|
For in-depth help on individual subcommands
|
|
</dt>
|
|
<dd>
|
|
<p>
|
|
<code># cset help <subcommand></code>
|
|
</p>
|
|
</dd>
|
|
<dt class="hdlist1">
|
|
For options of individual subcommands
|
|
</dt>
|
|
<dd>
|
|
<p>
|
|
<code># cset <subcommand> (-h | --help)</code>
|
|
</p>
|
|
</dd>
|
|
</dl></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div class="sect1">
|
|
<h2 id="_the_basic_shielding_model">2. The Basic Shielding Model</h2>
|
|
<div class="sectionbody">
|
|
<div class="paragraph"><p>Although any set up of cpusets can really be described as "shielding," there
|
|
is one prevalent shielding model in use that is so common that <strong>cset</strong> has a
|
|
subcommand that is dedicated to its use. This subcommand is called <code>shield</code>.</p></div>
|
|
<div class="paragraph"><p>The concept behind this model is the use of three cpusets. The <em>root</em> cpuset
|
|
which is always present in all configurations and contains all CPUs. The
|
|
<em>system</em> cpuset which contains CPUs which are used for system tasks. These
|
|
are the normal tasks that are not "important," but which need to run on the
|
|
system. And finally, the <em>user</em> cpuset which contains CPUs which are used for
|
|
"important" tasks. The <em>user</em> cpuset is the shield. Only those tasks that
|
|
are somehow important, usually tasks whose performance determines the overall
|
|
rating for the machine, are run in the <em>user</em> cpuset.</p></div>
|
|
<div class="paragraph"><p>The <code>shield</code> subcommand manages all of these cpusets and lets you define the
|
|
CPUs and Memory Nodes that are in the <em>shielded</em> and <em>unshielded</em> sets. The
|
|
subcommand automatically moves all movable tasks on the system into the
|
|
<em>unshielded</em> cpuset on shield activation, and back into the <em>root</em> cpuset on
|
|
shield tear down. The subcommand then lets you move tasks into and out of the
|
|
shield. Additionally, you can move special tasks (kernel threads) which
|
|
normally run in the <em>root</em> cpuset into the <em>unshielded</em> set so that your
|
|
shield will have even less disturbance.</p></div>
|
|
<div class="paragraph"><p>The <code>shield</code> subcommand abstracts the management of these cpusets away from
|
|
you and provides options that drive how the shield is set up, which tasks are
|
|
to be shielded and which tasks are not, and status of the shield. In fact,
|
|
you need not be bothered with the naming of the required cpusets or even where
|
|
the cpuset filesystem is mounted. <strong>Cset</strong> and the <code>shield</code> subcommand takes
|
|
care of all that.</p></div>
|
|
<div class="paragraph"><p>If you find yourself needing to define more cpusets for your application, then
|
|
it is likely that this simple shielding is not a rich enough model for you.
|
|
In this case, you should transition to using the <code>set</code> and <code>proc</code> subcommands
|
|
described in a later section.</p></div>
|
|
<div class="sect2">
|
|
<h3 id="_a_simple_shielding_example">2.1. A Simple Shielding Example</h3>
|
|
<div class="paragraph"><p>Assume that we have a 4-way machine that is not NUMA. This means there are 4
|
|
CPUs at our disposal and there is only one Memory Node available. On such
|
|
machines, we do not need to specify any memory node parameters to <strong>cset</strong>, it
|
|
sets up the only available memory node by default.</p></div>
|
|
<div class="paragraph"><p>Usually, one wants to dedicate as many CPUs to the shield as possible and
|
|
leave a minimal set of CPUs for normal system processing. The reasoning for
|
|
this is because the performance of the important tasks will rule the
|
|
performance of the installation as a whole and these important tasks need as
|
|
many resources available to them as possible, exclusive of other, unimportant
|
|
tasks that are running on the system.</p></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<div class="title">Note</div>
|
|
</td>
|
|
<td class="content">I use the word "task" to represent either a process or a thread that is
|
|
running on the system.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="sect3">
|
|
<h4 id="_setup_and_teardown_of_the_shield">2.1.1. Setup and Teardown of the Shield</h4>
|
|
<div class="paragraph"><p>To set up a shield of 3 CPUs with 1 CPU left for low priority system
|
|
processing, issue the following command.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset shield -c 1-3
|
|
cset: --> activating shielding:
|
|
cset: moving 176 tasks from root into system cpuset...
|
|
[==================================================]%
|
|
cset: "system" cpuset of CPUSPEC(0) with 176 tasks running
|
|
cset: "user" cpuset of CPUSPEC(1-3) with 0 tasks running</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>This command does a number of things. First, a <em>user</em> cpuset is created with
|
|
what’s called a CPUSPEC (CPU specification) from the <code>-c/--cpu</code> option. This
|
|
CPUSPEC specifies to use CPUs 1 through 3 inclusively. Next, the command
|
|
creates a <em>system</em> cpuset with a CPUSPEC that is the inverse of the <code>-c</code>
|
|
option for the current machine. On this machine that cpuset will only contain
|
|
the first CPU, CPU0. Next, all userspace processes running in the <em>root</em>
|
|
cpuset are transfered to the <em>system</em> cpuset. This makes all those processes
|
|
run only on CPU0. The effect of this is that the shield consists of CPUs 1
|
|
through 3 and they are now idling.</p></div>
|
|
<div class="paragraph"><p>Note that the command did not move the kernel threads that are running in the
|
|
<em>root</em> cpuset to the <em>system</em> cpuset. This is because you may want these
|
|
kernel threads to use all available CPUs. If you do not, the you can use the
|
|
<code>-k/--kthread</code> option as described below.</p></div>
|
|
<div class="paragraph"><p>The shield setup command above outputs the information of which cpusets were
|
|
created and how many tasks are running on each. If you want to see the
|
|
current status of the shield again, issue this command:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset shield
|
|
cset: --> shielding system active with
|
|
cset: "system" cpuset of CPUSPEC(0) with 176 tasks running
|
|
cset: "user" cpuset of CPUSPEC(1-3) with 0 tasks running</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Which shows us that the shield is set up and that 176 tasks are running in the
|
|
<em>system</em> cpuset—the "unshielded" cpuset.</p></div>
|
|
<div class="paragraph"><p>It is important to move all possible tasks from the <em>root</em> cpuset to the
|
|
unshielded <em>system</em> cpuset because a task’s cpuset property is inherited by
|
|
its children. Since we’ve moved all running tasks (including init) to the
|
|
unshielded <em>system</em> cpuset, that means that any new tasks that are spawned
|
|
will <strong>also</strong> run in the unshielded <em>system</em> cpuset.</p></div>
|
|
<div class="paragraph"><p>Some kernel threads can be moved into the unshielded <em>system</em> cpuset as well.
|
|
These are the threads that are not bound to specific CPUs. If a kernel thread
|
|
is bound to a specific CPU, then it is generally not a good idea to move that
|
|
thread to the <em>system</em> set because at worst it may hang the system and at best
|
|
it will slow the system down significantly. These threads are usually the IRQ
|
|
threads on a real time Linux kernel, for example, and you may want to not move
|
|
these kernel threads into <em>system</em>. If you leave them in the <em>root</em> cpuset,
|
|
then they will have access to all CPUs.</p></div>
|
|
<div class="paragraph"><p>However, if your application demands an even "quieter" shield, then you can
|
|
move all movable kernel threads into the unshielded <em>system</em> set with the
|
|
following command.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset shield -k on
|
|
cset: --> activating kthread shielding
|
|
cset: kthread shield activated, moving 70 tasks into system cpuset...
|
|
[==================================================]%
|
|
cset: done</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>You can see that this moved an additional 70 tasks to the unshielded <em>system</em>
|
|
cpuset. Note that the <code>-k/--kthread on</code> parameter can be given at the shield
|
|
creation time as well and you do not need to perform these two steps
|
|
separately if you know that you will want kernel thread shielding as well.
|
|
Executing <strong>cset shield</strong> again shows us the current state of the shield.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset shield
|
|
cset: --> shielding system active with
|
|
cset: "system" cpuset of CPUSPEC(0) with 246 tasks running
|
|
cset: "user" cpuset of CPUSPEC(1-3) with 0 tasks running</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>You can get a detailed listing of what is running in the shield by specifying
|
|
either <code>-s/--shield</code> or <code>-u/--unshield</code> to the <code>shield</code> subcommand and using
|
|
the verbose flag. You will get output similar to the following.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset shield --unshield -v
|
|
cset: "system" cpuset of CPUSPEC(0) with 251 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
root 1 0 Soth init [5]
|
|
root 2 0 Soth [kthreadd]
|
|
root 84 2 Sf50 [IRQ-9]
|
|
...
|
|
alext 31796 31789 Soth less
|
|
root 32653 25222 Roth python ./cset shield --unshield -v</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Note that I abbreviated the listing; we do have 251 tasks running in the
|
|
<em>system</em> set. The output is self-explanatory; however, the "SPPr" field may
|
|
need a little explanation. "SPPr" stands for State, Policy and Priority. You
|
|
can see that the initial two tasks are Stopped and running in timeshare
|
|
priority, marked as "oth" (for "other"). The [IRQ-9] task is also stopped,
|
|
but marked at real time FIFO policy with a priority of 50. The last task in
|
|
the listing is the <strong>cset</strong> command itself and is marked as running. Also note
|
|
that adding a second <code>-v/--verbose</code> option will not restrict the output to
|
|
fit into an 80 character screen.</p></div>
|
|
<div class="paragraph"><p>Tear down of the shield, stopping the shield in other words, is done with the
|
|
<code>-r/--reset</code> option to the <code>shield</code> subcommand. When this command is issued,
|
|
both the <em>system</em> and <em>user</em> cpusets are deleted and any tasks that are
|
|
running in both of those cpusets are moved to the <em>root</em> cpuset. Once so
|
|
moved, all tasks will have access to all resources on the system. For
|
|
example:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset shield --reset
|
|
cset: --> deactivating/reseting shielding
|
|
cset: moving 0 tasks from "/user" user set to root set...
|
|
cset: moving 250 tasks from "/system" system set to root set...
|
|
[==================================================]%
|
|
cset: deleting "/user" and "/system" sets
|
|
cset: done</code></pre>
|
|
</div></div>
|
|
</div>
|
|
<div class="sect3">
|
|
<h4 id="_moving_interesting_tasks_into_and_out_of_the_shield">2.1.2. Moving Interesting Tasks Into and Out of the Shield</h4>
|
|
<div class="paragraph"><p>Now that we have a shield running, the objective is to run our "important"
|
|
processes in that shield. These processes can be anything, but usually they
|
|
are directly related to the purpose of the machine. There are two ways to run
|
|
tasks in the shield:</p></div>
|
|
<div class="olist arabic"><ol class="arabic">
|
|
<li>
|
|
<p>
|
|
Exec a process into the shield
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
Move an already running task into the shield
|
|
</p>
|
|
</li>
|
|
</ol></div>
|
|
<div class="sect4">
|
|
<h5 id="_execing_a_process_into_the_shield">Execing a Process into the Shield</h5>
|
|
<div class="paragraph"><p>Running a new process in the shield can be done with the <code>-e/--exec</code> option
|
|
to the <code>shield</code> subcommand. This is the simplest way to get a task to run in
|
|
the shield. For this example, let’s exec a new bash shell into the shield
|
|
with the following commands.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset shield -s
|
|
cset: "user" cpuset of CPUSPEC(1-3) with 0 tasks running
|
|
cset: done
|
|
|
|
[zuul:cpuset-trunk]# cset shield -e bash
|
|
cset: --> last message, executed args into cpuset "/user", new pid is: 13300
|
|
|
|
[zuul:cpuset-trunk]# cset shield -s -v
|
|
cset: "user" cpuset of CPUSPEC(1-3) with 2 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
root 13300 8583 Soth bash
|
|
root 13329 13300 Roth python ./cset shield -s -v
|
|
|
|
[zuul:cpuset-trunk]# exit
|
|
|
|
[zuul:cpuset-trunk]# cset shield -s
|
|
cset: "user" cpuset of CPUSPEC(1-3) with 0 tasks running
|
|
cset: done</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>The first command above lists the status of the shield. We see that the
|
|
shield is defined as CPUs 1 through 3 inclusive and currently there are no
|
|
tasks running in it.</p></div>
|
|
<div class="paragraph"><p>The second command execs the bash shell into the shield with the <code>-e</code>
|
|
option. The last message of cset lists the PID of the new process.</p></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<div class="title">Note</div>
|
|
</td>
|
|
<td class="content"><strong>cset</strong> follows the tradition of separating the tool options from the
|
|
command to be execed options with a double dash (<code>--</code>). This is not shown in
|
|
this simple example, but if the command you want to exec also takes options,
|
|
separate them with the double dash like so: <code># cset shield -e mycommand -- -v</code>
|
|
The <code>-v</code> will be passed to <code>mycommand</code>, and not to <strong>cset</strong>.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="paragraph"><p>The next command lists the status of the shield again. You will note that
|
|
there are actually two tasks running shielded: our new shell and the <strong>cset</strong>
|
|
status command itself. Remember that the cpuset property of a task is
|
|
inherited by its children. Since we ran the new shell in the shield, its
|
|
child, which is the status command, also ran in the shield.</p></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<div class="title">Tip</div>
|
|
</td>
|
|
<td class="content">Execing a shell into the shield is a useful way to experiment with
|
|
running tasks in the shield since all children of the shell will also run in
|
|
the shield.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="paragraph"><p>The last command exits the shell after which we request a shield status again
|
|
and see that once again, it does not contain any tasks.</p></div>
|
|
<div class="paragraph"><p>You may have noticed in the output above that both the new shell and the
|
|
status command are running as the root user. This is because <strong>cset</strong> needs to
|
|
run as root and so all it’s children will also run as root. If you need to
|
|
run a process under a different user and or group, you may use the <code>--user</code>
|
|
and <code>--group</code> options for <code>exec</code> as follows.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset shield --user=alext --group=users -e bash
|
|
cset: --> last message, executed args into cpuset "/user", new pid is: 14212
|
|
|
|
alext@zuul> cset shield -s -v
|
|
cset: "user" cpuset of CPUSPEC(1-3) with 2 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
alext 14212 8583 Soth bash
|
|
alext 14241 14212 Roth python ./cset shield -s -v</code></pre>
|
|
</div></div>
|
|
</div>
|
|
<div class="sect4">
|
|
<h5 id="_moving_a_running_task_into_and_out_of_the_shield">Moving a Running Task into and out of the Shield</h5>
|
|
<div class="paragraph"><p>While execing a process into the shield is undoubtably useful, most of the
|
|
time, you’ll want to move already running tasks into and out of the shield.
|
|
The <strong>cset</strong> shield subcommand includes two options for doing this:
|
|
<code>-s/--shield</code> and <code>-u/--unshield</code>. These options require what’s called a
|
|
PIDSPEC (process specification) to also be specified with the <code>-p/--pid</code>
|
|
option. The PIDSPEC defines which tasks get operated on. The PIDSPEC can be
|
|
a single process ID, a list of process IDs separated by commas, and a list of
|
|
process ID ranges separated by dashes, groups of which are separated by
|
|
commas. For example:</p></div>
|
|
<div class="dlist"><dl>
|
|
<dt class="hdlist1">
|
|
<code>--shield --pid 1234</code>
|
|
</dt>
|
|
<dd>
|
|
<p>
|
|
This PIDSPEC argument specifies that PID 1234 be shielded.
|
|
</p>
|
|
</dd>
|
|
<dt class="hdlist1">
|
|
<code>--shield --pid 1234,42,1934,15000,15001,15002</code>
|
|
</dt>
|
|
<dd>
|
|
<p>
|
|
This PIDSPEC argument specifies that this list of PIDs only be moved into the
|
|
shield.
|
|
</p>
|
|
</dd>
|
|
<dt class="hdlist1">
|
|
<code>--unshield -p 5000,5100,6010-7000,9232</code>
|
|
</dt>
|
|
<dd>
|
|
<p>
|
|
This PIDSPEC argument specifies that PIDs 5000,5100 and 9232 be unshielded
|
|
(moved out of the shield) along with any existing PID that is in the range
|
|
6010 through 7000 inclusive.
|
|
</p>
|
|
</dd>
|
|
</dl></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<div class="title">Note</div>
|
|
</td>
|
|
<td class="content">A range in a PIDSPEC does not have to have tasks running for every
|
|
number in that range. In fact, it is not even an error if there are no tasks
|
|
running in that range; none will be moved in that case. The range simply
|
|
specifies to act on any tasks that have a PID or TID that is within that
|
|
range.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="paragraph"><p>Use of the appropriate PIDSPEC can thus be handy to move tasks and groups of
|
|
tasks into and out of the shield. Additionally, there is one more option that
|
|
can help with multi-threaded processes, and that is the <code>--threads</code> flag. If
|
|
this flag is present in a <code>shield</code> or <code>unshield</code> command with a PIDSPEC and if
|
|
any of the task IDs in the PIDSPEC belong to a thread in a process container,
|
|
then <strong>all</strong> the sibling threads in that process container will get shielded or
|
|
unshielded as well. This flag provides an easy mechanism to shield/unshield
|
|
all threads of a process by simply specifying one thread in that process.</p></div>
|
|
<div class="paragraph"><p>In the following example, we move the current shell into the shield with a
|
|
range PIDSPEC and back out with the bash variable for the current PID.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# echo $$
|
|
22018
|
|
|
|
[zuul:cpuset-trunk]# cset shield -s -p 22010-22020
|
|
cset: --> shielding following pidspec: 22010-22020
|
|
cset: done
|
|
|
|
[zuul:cpuset-trunk]# cset shield -s -v
|
|
cset: "user" cpuset of CPUSPEC(1-3) with 2 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
root 3770 22018 Roth python ./cset shield -s -v
|
|
root 22018 5034 Soth bash
|
|
cset: done
|
|
|
|
[zuul:cpuset-trunk]# cset shield -u -p $$
|
|
cset: --> unshielding following pidspec: 22018
|
|
cset: done
|
|
|
|
[zuul:cpuset-trunk]# cset shield -s
|
|
cset: "user" cpuset of CPUSPEC(1-3) with 0 tasks running
|
|
cset: done</code></pre>
|
|
</div></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<div class="title">Note</div>
|
|
</td>
|
|
<td class="content">Ordinarily, the <code>shield</code> option will shield a PIDSPEC only if it is
|
|
currently running in the <em>system</em> set—the unshielded set. The <code>unshield</code>
|
|
option will unshield a PIDSPEC only if it is currently running in the <em>user</em>
|
|
set—the shielded set. If you want to <code>shield/unshield</code> a process that
|
|
happens to be running in the <em>root</em> set (not common), then use the <code>--force</code>
|
|
option for these commands.</td>
|
|
</tr></table>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div class="sect1">
|
|
<h2 id="_full_featured_cpuset_manipulation_commands">3. Full Featured Cpuset Manipulation Commands</h2>
|
|
<div class="sectionbody">
|
|
<div class="paragraph"><p>While basic shielding as described above is useful and a common use model for
|
|
<strong>cset</strong>, there comes a time when more functionality will be desired to
|
|
implement your strategy. To implement this, <strong>cset</strong> provides two subcommands:
|
|
<code>set</code>, which allows you to manipulate cpusets; and <code>proc</code>, which allows you to
|
|
manipulate processes within those cpusets.</p></div>
|
|
<div class="sect2">
|
|
<h3 id="_the_set_subcommand">3.1. The Set Subcommand</h3>
|
|
<div class="paragraph"><p>In order to do anything with cpusets, you must be able to create, adjust,
|
|
rename, move and destroy them. The <code>set</code> subcommand allows the management of
|
|
cpusets in such a manner.</p></div>
|
|
<div class="sect3">
|
|
<h4 id="_creating_and_destroying_cpusets_with_set">3.1.1. Creating and Destroying Cpusets with Set</h4>
|
|
<div class="paragraph"><p>The basic syntax of <code>set</code> for cpuset creation is:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -c 1-3 -s my_cpuset1
|
|
cset: --> created cpuset "my_cpuset1"</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>This creates a cpuset named "my_cpuset1" with a CPUSPEC of CPU1, CPU2 and
|
|
CPU3. The CPUSPEC is the same concept as described in the "Setup and
|
|
Teardown of the Shield" section above. The <code>set</code> subcommand also takes a
|
|
<code>-m/--mem</code> option that lets you specify the memory nodes the set will use as
|
|
well as flags to make the CPUs and MEMs exclusive to the cpuset. If you are
|
|
on a non-NUMA machine, just leave the <code>-m</code> option out and the default memory
|
|
node 0 will be used.</p></div>
|
|
<div class="paragraph"><p>Just like with <code>shield</code>, you can adjust the CPUs and MEMs with subsequent
|
|
calls to <code>set</code>. If, for example, you wish to adjust the "my_cpuset1" cpuset
|
|
to only use CPUs 1 and 3 (and omit CPU2), then issue the following command.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -c 1,3 -s my_cpuset1
|
|
cset: --> modified cpuset "my_cpuset</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p><strong>cset</strong> will then adjust the CPUs that are assigned to the "my_cpuset1" set to
|
|
only use CPU1 and CPU3.</p></div>
|
|
<div class="paragraph"><p>To rename a cpuset, use the <code>-n/--newname</code> option. For example:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -s my_cpuset1 -n super_set
|
|
cset: --> renaming "/cpusets/my_cpuset1" to "super_set"</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Renames the cpuset called "my_cpuset1" to "super_set".</p></div>
|
|
<div class="paragraph"><p>To destroy a cpuset, use the <code>-d/--destroy</code> option as follows.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -d super_set
|
|
cset: --> processing cpuset "super_set", moving 0 tasks to parent "/"...
|
|
cset: --> deleting cpuset "/super_set"
|
|
cset: done</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>This command destroys the newly created cpuset called "super_set". When a
|
|
cpuset is destroyed, all the tasks running in it are moved to the parent
|
|
cpuset. The <em>root</em> cpuset, which always exists and always contains all CPUs,
|
|
can not be destroyed. You may also give the <code>--destroy</code> option a list of
|
|
cpusets to destroy.</p></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<div class="title">Note</div>
|
|
</td>
|
|
<td class="content">The <strong>cset</strong> subcommand creates the cpusets based on a mounted cpuset
|
|
filesystem. You do not need to know where that filesystem is mounted,
|
|
although it is easy to figure out (by default it’s on <em>/cpusets</em>). When you
|
|
give the <code>set</code> subcommand a name for a new cpuset, it is created wherever the
|
|
cpuset filesystem is mounted at.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="paragraph"><p>If you want to create a cpuset hierarchy, then you must give a path to the
|
|
<strong>cset</strong> <code>set</code> subcommand. This path will always begin with the <em>root</em> cpuset,
|
|
for which the path is <em>/</em>. For example.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -c 1,3 -s top_set
|
|
cset: --> created cpuset "top_set"
|
|
|
|
[zuul:cpuset-trunk]# cset set -c 3 -s /top_set/sub_set
|
|
cset: --> created cpuset "/top_set/sub_set"</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>These commands created two cpusets: <em>top_set</em> and <em>sub_set</em>. The <em>top_set</em>
|
|
uses CPU1 and CPU3. It has a subset of <em>sub_set</em> which only uses CPU3. Once
|
|
you have created a subset with a path, then if the name is unique, you do not
|
|
have to specify the path in order to affect it. If the name is not unique,
|
|
then <strong>cset</strong> will complain and ask you to use the path. For example:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -c 1,3 -s sub_set
|
|
cset: --> modified cpuset "sub_set</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>This command adds CPU1 to the <em>sub_set</em> cpuset for it’s use. Note that using
|
|
the path in this case is optional.</p></div>
|
|
<div class="paragraph"><p>If you attempt to destroy a cpuset which has sub-cpusets, <strong>cset</strong> will complain
|
|
and not do it unless you use the <code>-r/--recurse</code> and the <code>--force</code> options.
|
|
If you do use <code>--force</code>, then all the tasks running in all subsets of the
|
|
deletion target cpuset will be moved to the target’s parent cpuset and all
|
|
cpusets.</p></div>
|
|
<div class="paragraph"><p>Moving a cpuset from under a certain cpuset to a different location is
|
|
currently not implemented and is slated for a later release of <strong>cset</strong>.</p></div>
|
|
</div>
|
|
<div class="sect3">
|
|
<h4 id="_listing_cpusets_with_set">3.1.2. Listing Cpusets with Set</h4>
|
|
<div class="paragraph"><p>To list cpusets, use the <code>set</code> subcommand with the <em>-l/--list</em> option. For
|
|
example:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -l
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
root 0-3 y 0 y 320 1 /
|
|
one 3 n 0 n 0 1 /one</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>This shows that there is currently one cpuset present called <em>one</em>. (Of course
|
|
that there is also the <em>root</em> set, which is always present.) The output shows
|
|
that the <em>one</em> cpuset has no tasks running in it. The <em>root</em> cpuset has 320
|
|
tasks running. The "-X" for "CPUs" and "MEMs" fields denotes whether the CPUs
|
|
and MEMs in the cpusets are marked exclusive to those cpusets. Note that the
|
|
<em>one</em> cpuset has subsets as indicated by a 1 in the <em>Subs</em> field. You can
|
|
specify a cpuset to list with the <code>set</code> subcommand as follows.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -l -s one
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
one 3 n 0 n 0 1 /one
|
|
two 3 n 0 n 0 1 /one/two</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>This output shows that there is a cpuset called <em>two</em> in cpuset <em>one</em> and it
|
|
also has subset. You can also ask for a recursive listing as follows.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -l -r
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
root 0-3 y 0 y 320 1 /
|
|
one 3 n 0 n 0 1 /one
|
|
two 3 n 0 n 0 1 /one/two
|
|
three 3 n 0 n 0 0 /one/two/three</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>This command lists all cpusets existing on the system since it asks for a
|
|
recursive listing beginning at the <em>root</em> cpuset. Incidentally, should you
|
|
need to specify the <em>root</em> cpuset you can use either <code>root</code> or <code>/</code> to specify it
|
|
explicitely—just remember that the <em>root</em> cpuset cannot be deleted or modified.</p></div>
|
|
</div>
|
|
</div>
|
|
<div class="sect2">
|
|
<h3 id="_the_proc_subcommand">3.2. The Proc Subcommand</h3>
|
|
<div class="paragraph"><p>Now that we know how to create, rename and destroy cpusets with the <code>set</code>
|
|
subcommand, the next step is to manage threads and processes in those
|
|
cpusets. The subcommand to do this is called <code>proc</code> and it allows you to exec
|
|
processes into a cpuset, move existing tasks around existing cpusets, and list
|
|
tasks running in specified cpusets. For the following examples, let us
|
|
assume a cpuset setup of two sets as follows:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -l
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
root 0-3 y 0 y 309 2 /
|
|
two 2 n 0 n 3 0 /two
|
|
three 3 n 0 n 10 0 /three</code></pre>
|
|
</div></div>
|
|
<div class="sect3">
|
|
<h4 id="_listing_tasks_with_proc">3.2.1. Listing Tasks with Proc</h4>
|
|
<div class="paragraph"><p>Operation of the <code>proc</code> subcommand follows the same model as the <code>set</code>
|
|
subcommand. For example, to list tasks in a cpuset, you need to use the
|
|
<code>-l/--list</code> option and specify the cpuset by name or, if the name exists
|
|
multiple times in the cpuset hierarchy, by path. For example:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -l -s two
|
|
cset: "two" cpuset of CPUSPEC(2) with 3 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
root 16141 4300 Soth bash
|
|
root 16171 16141 Soth bash
|
|
root 16703 16171 Roth python ./cset proc -l two</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>This output shows us that the cpuset called <em>two</em> has CPU2 only attached to it
|
|
and is running three tasks: two shells and the python command to list it.
|
|
Note that cpusets are inherited so that if a process is contained in a cpuset,
|
|
then any children it spawns also run within that set. In this case, the
|
|
python command to list set <em>two</em> was run from a shell already running in set
|
|
<em>two</em>. This can be seen by the PPID (parent process ID) of the python
|
|
command matching the PID of the shell.</p></div>
|
|
<div class="paragraph"><p>Additionally, the "SPPr" field needs explanation. "SPPr" stands for State,
|
|
Policy and Priority. You can see that the initial two tasks are Stopped and
|
|
running in timeshare priority, marked as "oth" (for "other"). The last task
|
|
is marked as running, "R" and also at timeshare priority, "oth." If any of
|
|
these tasks would have been at real time priority, then the policy would be
|
|
shown as "f" for FIFO or "r" for round robin, and the priority would be a
|
|
number from 1 to 99. See below for an example.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -l -s root | head -7
|
|
cset: "root" cpuset of CPUSPEC(0-3) with 309 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
root 1 0 Soth init [5]
|
|
root 2 0 Soth [kthreadd]
|
|
root 3 2 Sf99 [migration/0]
|
|
root 4 2 Sf99 [posix_cpu_timer]</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>This output shows the first few tasks in the <em>root</em> cpuset. Note that both
|
|
<em>init</em> and <em>[kthread]</em> are running at timeshare; however, the <em>[migration/0]</em>
|
|
and <em>[posix_cpu_timer]</em> kernel threads are running at real time policy of FIFO
|
|
and priority of 99. Incidentally, this output is from a system running the
|
|
real time Linux kernel which runs some kernel threads at real time
|
|
priorities. And finally, note that you can of course use <strong>cset</strong> as any other
|
|
Linux tool and include it in pipelines as in the example above.</p></div>
|
|
<div class="paragraph"><p>Taking a peek into the third cpuset called <em>three</em>, we see:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -l -s three
|
|
cset: "three" cpuset of CPUSPEC(3) with 10 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
alext 16165 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16169 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16170 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16237 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16491 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16492 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16493 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 17243 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 17244 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 17265 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>This output shows that a lot of <em>beagled</em> tasks are running in this cpuset and
|
|
it also shows an ellipsis (…) at the end of their listings. If you see this
|
|
ellipsis, that means that the command was too long to fit onto an 80 character
|
|
screen. To see the entire commandline, use the <code>-v/--verbose</code> flag, as per
|
|
following.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -l -s three -v | head -4
|
|
cset: "three" cpuset of CPUSPEC(3) with 10 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
alext 16165 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg --autostarted --indexing-delay 300</code></pre>
|
|
</div></div>
|
|
</div>
|
|
<div class="sect3">
|
|
<h4 id="_execing_tasks_with_proc">3.2.2. Execing Tasks with Proc</h4>
|
|
<div class="paragraph"><p>To exec a task into a cpuset, the <code>proc</code> subcommand needs to be employed with
|
|
the <code>-e/--exec</code> option. Let’s exec a shell into the cpuset named <em>two</em> in
|
|
our set. First we check to see what is running that set:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -l -s two
|
|
cset: "two" cpuset of CPUSPEC(2) with 0 tasks running
|
|
|
|
[zuul:cpuset-trunk]# cset proc -s two -e bash
|
|
cset: --> last message, executed args into cpuset "/two", new pid is: 20955
|
|
|
|
[zuul:cpuset-trunk]# cset proc -l -s two
|
|
cset: "two" cpuset of CPUSPEC(2) with 2 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
root 20955 19253 Soth bash
|
|
root 20981 20955 Roth python ./cset proc -l two</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>You can see that initially, <em>two</em> had nothing running in it. After the
|
|
completion of the second command, we list <em>two</em> again and see that there are
|
|
two tasks running: the shell which we execed and the python <strong>cset</strong> command
|
|
that is listing the cpuset. The reason for the second task is that the cpuset
|
|
property of a running task is inherited by all its children. Since we
|
|
executed the listing command from the new shell which was bound to cpuset
|
|
<em>two</em>, the resulting process for the listing is also bound to cpuset <em>two</em>.
|
|
Let’s test that by just running a new shell with no prefixed <strong>cset</strong> command.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# bash
|
|
|
|
[zuul:cpuset-trunk]# cset proc -l -s two
|
|
cset: "two" cpuset of CPUSPEC(2) with 3 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
root 20955 19253 Soth bash
|
|
root 21118 20955 Soth bash
|
|
root 21147 21118 Roth python ./cset proc -l two</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Here again we see that the second shell, PID 21118, has a parent PID of 20955
|
|
which is the first shell. Both shells as well as the listing command are
|
|
running in the <em>two</em> cpuset.</p></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<div class="title">Note</div>
|
|
</td>
|
|
<td class="content"><strong>cset</strong> follows the tradition of separating the tool options from the
|
|
command to be execed options with a double dash (<code>--</code>). This is not shown in
|
|
this simple example, but if the command you want to exec also takes options,
|
|
separate them with the double dash like so: <code># cset proc -s myset -e mycommand
|
|
-- -v</code> The <code>-v</code> will be passed to <code>mycommand</code>, and not to <strong>cset</strong>.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<div class="title">Tip</div>
|
|
</td>
|
|
<td class="content">Execing a shell into a cpuset is a useful way to experiment with running
|
|
tasks in that cpuset since all children of the shell will also run in the same
|
|
cpuset.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="paragraph"><p>Finally, if you misspell the command to be execed, the result may be
|
|
puzzling. For example:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -s two -e blah-blah
|
|
cset: --> last message, executed args into cpuset "/two", new pid is: 21655
|
|
cset: **> [Errno 2] No such file or directory</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>The result is no new process even though a new PID is output. The reason for
|
|
the message is of course that the <strong>cset</strong> process forked in preparation for
|
|
exec, but the command <code>blah-blah</code> was not found in order to exec it.</p></div>
|
|
</div>
|
|
<div class="sect3">
|
|
<h4 id="_moving_tasks_with_proc">3.2.3. Moving Tasks with Proc</h4>
|
|
<div class="paragraph"><p>Although the ability to exec a task into a cpuset is fundamental, you will
|
|
most likely be moving tasks between cpusets more often. Moving tasks is
|
|
accomplished with the <code>-m/--move</code> and <code>-p/--pid</code> options to the <code>proc</code>
|
|
subcommand of <strong>cset</strong>. The move option tells the <code>proc</code> subcommand that a task
|
|
move is requested. The <code>-p/--pid</code> option takes an argument called a PIDSPEC
|
|
(PID Specification). The PIDSPEC defines which tasks get operated on.</p></div>
|
|
<div class="paragraph"><p>The PIDSPEC can be a single process ID, a list of process IDs separated by
|
|
commas, and a list of process ID ranges also separated by commas. For
|
|
example:</p></div>
|
|
<div class="dlist"><dl>
|
|
<dt class="hdlist1">
|
|
<code>--move --pid 1234</code>
|
|
</dt>
|
|
<dd>
|
|
<p>
|
|
This PIDSPEC argument specifies that task 1234 be moved.
|
|
</p>
|
|
</dd>
|
|
<dt class="hdlist1">
|
|
<code>--move --pid 1234,42,1934,15000,15001,15002</code>
|
|
</dt>
|
|
<dd>
|
|
<p>
|
|
This PIDSPEC argument specifies that this list of tasks only be moved.
|
|
</p>
|
|
</dd>
|
|
<dt class="hdlist1">
|
|
<code>--move --pid 5000,5100,6010-7000,9232</code>
|
|
</dt>
|
|
<dd>
|
|
<p>
|
|
This PIDSPEC argument specifies that tasks 5000,5100 and 9232 be moved along
|
|
with any existing task that is in the range 6010 through 7000 inclusive.
|
|
</p>
|
|
</dd>
|
|
</dl></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<div class="title">Note</div>
|
|
</td>
|
|
<td class="content">A range in a PIDSPEC does not have to have running tasks for every
|
|
number in that range. In fact, it is not even an error if there are no tasks
|
|
running in that range; none will be moved in that case. The range simply
|
|
specifies to act on any tasks that have a PID or TID that is within that
|
|
range.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="paragraph"><p>In the following example, we move the current shell into the cpuset named
|
|
<em>two</em> with a range PIDSPEC and back out to the <em>root</em> cpuset with the bash
|
|
variable for the current PID.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -l -s two
|
|
cset: "two" cpuset of CPUSPEC(2) with 0 tasks running
|
|
|
|
[zuul:cpuset-trunk]# echo $$
|
|
19253
|
|
|
|
[zuul:cpuset-trunk]# cset proc -m -p 19250-19260 -t two
|
|
cset: moving following pidspec: 19253
|
|
cset: moving 1 userspace tasks to /two
|
|
cset: done
|
|
|
|
[zuul:cpuset-trunk]# cset proc -l -s two
|
|
cset: "two" cpuset of CPUSPEC(2) with 2 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
root 19253 16447 Roth bash
|
|
root 29456 19253 Roth python ./cset proc -l -s two
|
|
|
|
[zuul:cpuset-trunk]# cset proc -m -p $$ -t root
|
|
cset: moving following pidspec: 19253
|
|
cset: moving 1 userspace tasks to /
|
|
cset: done
|
|
|
|
[zuul:cpuset-trunk]# cset proc -l -s two
|
|
cset: "two" cpuset of CPUSPEC(2) with 0 tasks running</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Use of the appropriate PIDSPEC can thus be handy to move tasks and groups of
|
|
tasks. Additionally, there is one more option that can help with
|
|
multi-threaded processes, and that is the <code>--threads</code> flag. If this flag is
|
|
present in a <code>proc</code> move command with a PIDSPEC and if any of the task IDs in
|
|
the PIDSPEC belongs to a thread in a process container, then <strong>all</strong> the sibling
|
|
threads in that process container will also get moved. This flag provides an
|
|
easy mechanism to move all threads of a process by simply specifying one
|
|
thread in that process. In the following example, we move all the threads
|
|
running in cpuset <em>three</em> to cpuset <em>two</em> by using the <code>--threads</code> flag.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set two three
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
two 2 n 0 n 0 0 /two
|
|
three 3 n 0 n 10 0 /three
|
|
|
|
[zuul:cpuset-trunk]# cset proc -l -s three
|
|
cset: "three" cpuset of CPUSPEC(3) with 10 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
alext 16165 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16169 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16170 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16237 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16491 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16492 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16493 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 17243 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 17244 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 27133 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
|
|
[zuul:cpuset-trunk]# cset proc -m -p 16165 --threads -t two
|
|
cset: moving following pidspec: 16491,16493,16492,16170,16165,16169,27133,17244,17243,16237
|
|
cset: moving 10 userspace tasks to /two
|
|
[==================================================]%
|
|
cset: done
|
|
|
|
[zuul:cpuset-trunk]# cset set two three
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
two 2 n 0 n 10 0 /two
|
|
three 3 n 0 n 0 0 /three</code></pre>
|
|
</div></div>
|
|
<div class="sect4">
|
|
<h5 id="_moving_all_tasks_from_one_cpuset_to_another">Moving All Tasks from one Cpuset to Another</h5>
|
|
<div class="paragraph"><p>There is a special case for moving all tasks currently running in one cpuset
|
|
to another. This can be a common use case, and when you need to do it,
|
|
specifying a PIDSPEC with <code>-p</code> is not necessary <em>so long as</em> you use the
|
|
<code>-f/--fromset</code> <strong>and</strong> the <code>-t/--toset</code> options.</p></div>
|
|
<div class="paragraph"><p>In the following example, we move all 10 <code>beagled</code> threads back to cpuset
|
|
<em>three</em> with this method.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -l two three
|
|
cset: "two" cpuset of CPUSPEC(2) with 10 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
alext 16165 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16169 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16170 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16237 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16491 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16492 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 16493 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 17243 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 17244 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
alext 27133 1 Soth beagled /usr/lib64/beagle/BeagleDaemon.exe --bg -...
|
|
cset: "three" cpuset of CPUSPEC(3) with 0 tasks running
|
|
|
|
[zuul:cpuset-trunk]# cset proc -m -f two -t three
|
|
cset: moving all tasks from two to /three
|
|
cset: moving 10 userspace tasks to /three
|
|
[==================================================]%
|
|
cset: done
|
|
|
|
[zuul:cpuset-trunk]# cset set two three
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
two 2 n 0 n 0 0 /two
|
|
three 3 n 0 n 10 0 /three</code></pre>
|
|
</div></div>
|
|
</div>
|
|
<div class="sect4">
|
|
<h5 id="_moving_kernel_threads_with_proc">Moving Kernel Threads with Proc</h5>
|
|
<div class="paragraph"><p>Kernel threads are special and <strong>cset</strong> detects tasks that are kernel threads
|
|
and will refuse to move them unless you also add a <code>-k/--kthread</code> option to
|
|
your <code>proc</code> move command. Even if you include <code>-k</code>, <strong>cset</strong> will <em>still</em>
|
|
refuse to move the kernel thread if they are bound to specific CPUs. The
|
|
reason for this is system protection.</p></div>
|
|
<div class="paragraph"><p>A number of kernel threads, especially on the real time Linux kernel, are
|
|
bound to specific CPUs and depend on per-CPU kernel variables. If you move
|
|
these threads to a different CPU than what they are bound to, you risk at best
|
|
that the system will become horribly slow, and at worst a system hang. If you
|
|
still insist to move those threads (after all, <strong>cset</strong> needs to give the
|
|
knowledgeable user access to the keys), then you need to use the <code>--force</code>
|
|
option additionally.</p></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<div class="title">Warning</div>
|
|
</td>
|
|
<td class="content">Overriding a task move command with <code>--force</code> can have dire
|
|
consequences for the system. Please be sure of the command before you force
|
|
it.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="paragraph"><p>In the following example, we move all unbound kernel threads running in the
|
|
<em>root</em> cpuset to the cpuset named <em>two</em> by using the <code>-k</code> option.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -k -f root -t two
|
|
cset: moving all kernel threads from / to /two
|
|
cset: moving 70 kernel threads to: /two
|
|
cset: --> not moving 76 threads (not unbound, use --force)
|
|
[==================================================]%
|
|
cset: done</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>You will note that we used the fromset→toset facility of the <code>proc</code>
|
|
subcommand and we only specified the <code>-k</code> option (not the <code>-m</code> option). This
|
|
has the effect of moving all kernel threads only.</p></div>
|
|
<div class="paragraph"><p>Note that only 70 actual kernel threads were moved and 76 were not. The
|
|
reason that 76 kernel threads were not moved was because they are bound to
|
|
specific CPUs. Now, let’s move those kernel threads back to <em>root</em>.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -k -f two -t root
|
|
cset: moving all kernel threads from /two to /
|
|
cset: ** no task matched move criteria
|
|
cset: **> kernel tasks are bound, use --force if ok
|
|
|
|
[zuul:cpuset-trunk]# cset set -l -s two
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
two 2 n 0 n 70 0 /two</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Ah! What’s this? <strong>Cset</strong> refused to move the kernel threads back to <em>root</em>
|
|
because it says that they are "bound." Let’s check this with the Linux
|
|
taskset command.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -l -s two | head -5
|
|
cset: "two" cpuset of CPUSPEC(2) with 70 tasks running
|
|
USER PID PPID SPPr TASK NAME
|
|
-------- ----- ----- ---- ---------
|
|
root 2 0 Soth [kthreadd]
|
|
root 55 2 Soth [khelper]
|
|
|
|
[zuul:cpuset-trunk]# taskset -p 2
|
|
pid 2's current affinity mask: 4
|
|
|
|
[zuul:cpuset-trunk]# cset set -l -s two
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
two 2 n 0 n 70 0 /two</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Of course, since the cpuset named <em>two</em> only has CPU2 assigned to it, once we
|
|
moved the unbound kernel threads from <em>root</em> to <em>two</em>, their affinity masks
|
|
got automatically changed to only use CPU2. This is evident from the
|
|
<code>taskset</code> output which is a hex value. To really move these threads back to
|
|
<em>root</em>, we need to force the move as follows.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -k -f two -t root --force
|
|
cset: moving all kernel threads from /two to /
|
|
cset: moving 70 kernel threads to: /
|
|
[==================================================]%
|
|
cset: done</code></pre>
|
|
</div></div>
|
|
</div>
|
|
</div>
|
|
<div class="sect3">
|
|
<h4 id="_destroying_tasks">3.2.4. Destroying Tasks</h4>
|
|
<div class="paragraph"><p>There actually is no <strong>cset</strong> subcommand or option to destroy tasks—it’s not
|
|
really needed. Tasks exist and are accessible on the system as normal, even
|
|
if they happen to be running in one cpuset or another. To destroy tasks, use
|
|
the usual ^C method or by using the <strong>kill(1)</strong> command.</p></div>
|
|
</div>
|
|
</div>
|
|
<div class="sect2">
|
|
<h3 id="_implementing_shielding_with_set_and_proc">3.3. Implementing "Shielding" with Set and Proc</h3>
|
|
<div class="paragraph"><p>With the preceding material on the <code>set</code> and <code>proc</code> subcommands, we now have
|
|
the background to implement the basic shielding model, just like the <code>shield</code>
|
|
subcommand.</p></div>
|
|
<div class="paragraph"><p>One may pose the question as to why we want to do this, especially since
|
|
<code>shield</code> already does it? The answer is that sometimes one needs more
|
|
functionality than <code>shield</code> has to implement one’s shielding strategy. In
|
|
those case you need to first stop using <code>shield</code> since that subcommand will
|
|
interfere with the further application of <code>set</code> and <code>proc</code>; however, you will
|
|
still need to implement the functionality of <code>shield</code> in order to implement
|
|
successful shielding.</p></div>
|
|
<div class="paragraph"><p>Remember from the above sections describing <code>shield</code>, that shielding has at
|
|
minimum three cpusets: <em>root</em>, which is always present and contains all CPUs;
|
|
<em>system</em> which is the "non-shielded" set of CPUs and runs unimportant system
|
|
tasks; and <em>user</em>, which is the "shielded" set of CPUs and runs your important
|
|
tasks. Remember also that <code>shield</code> moves all movable tasks into <em>system</em>
|
|
and, optionally, moves unbound kernel threads into <em>system</em> as well.</p></div>
|
|
<div class="paragraph"><p>We start first by creating the <em>system</em> and <em>user</em> cpusets as follows. We
|
|
assume that the machine is a four-CPU machine without NUMA memory features.
|
|
The <em>system</em> cpuset should hold only CPU0 while the <em>user</em> cpuset should hold
|
|
the rest of the CPUs.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -c 0 -s system
|
|
cset: --> created cpuset "system"
|
|
|
|
[zuul:cpuset-trunk]# cset set -c 1-3 -s user
|
|
cset: --> created cpuset "user"
|
|
|
|
[zuul:cpuset-trunk]# cset set -l
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
root 0-3 y 0 y 333 2 /
|
|
user 1-3 n 0 n 0 0 /user
|
|
system 0 n 0 n 0 0 /system</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Now, we need to move all running user processes into the <em>system</em> cpuset.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -m -f root -t system
|
|
cset: moving all tasks from root to /system
|
|
cset: moving 188 userspace tasks to /system
|
|
[==================================================]%
|
|
cset: done
|
|
|
|
[zuul:cpuset-trunk]# cset set -l
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
root 0-3 y 0 y 146 2 /
|
|
user 1-3 n 0 n 0 0 /user
|
|
system 0 n 0 n 187 0 /system</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>We now have the basic shielding set up. Since all userspace tasks are running
|
|
in <em>system</em>, anything that is spawned from them will also run in <em>system</em>.
|
|
The <em>user</em> cpuset has nothing running in it unless you put tasks there with
|
|
the <code>proc</code> subcommand as described above. If you also want to move movable
|
|
kernel threads from <em>root</em> to <em>system</em> (in order to achieve a form of
|
|
"interrupt shielding" on a real time Linux kernel for example), you would
|
|
execute the following command as well.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -k -f root -t system
|
|
cset: moving all kernel threads from / to /system
|
|
cset: moving 70 kernel threads to: /system
|
|
cset: --> not moving 76 threads (not unbound, use --force)
|
|
[==================================================]%
|
|
cset: done
|
|
|
|
[zuul:cpuset-trunk]# cset set -l
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
root 0-3 y 0 y 76 2 /
|
|
user 1-3 n 0 n 0 0 /user
|
|
system 0 n 0 n 257 0 /system</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>At this point, you have achieved the simple shielding model that the <code>shield</code>
|
|
subcommand provides. You can now add other cpuset definitions to expand your
|
|
shielding strategy beyond that simple model.</p></div>
|
|
</div>
|
|
<div class="sect2">
|
|
<h3 id="_implementing_hierarchy_with_set_and_proc">3.4. Implementing Hierarchy with Set and Proc</h3>
|
|
<div class="paragraph"><p>One popular extended "shielding" model is based on hierarchical cpusets, each
|
|
with diminishing numbers of CPUs. This model is used to create "priority
|
|
cpusets" that allow assignment of CPU resources to tasks based on some
|
|
arbitrary priority definition. The idea being that a higher priority task
|
|
will get access to more CPU resources than a lower priority task.</p></div>
|
|
<div class="paragraph"><p>The example provided here once again assumes a machine with four CPUs and no
|
|
NUMA memory features. This base serves to illustrate the point well; however,
|
|
note that if your machine has (many) more CPUs, then strategies such as this
|
|
and others get more interesting.</p></div>
|
|
<div class="paragraph"><p>We define a shielding set up as in the previous section where we have a
|
|
<em>system</em> cpuset with just CPU0 that takes care of "unimportant" system tasks.
|
|
One usually requires this type of cpuset since it forms the basis of
|
|
shielding. We modify the strategy to not use a <em>user</em> cpuset, instead we
|
|
create a number of new cpusets each holding one more CPU than the other.
|
|
These cpusets will be called <em>prio_low</em> with one CPU, <em>prio_med</em> with two
|
|
CPUs, <em>prio_high</em> with three CPUs, and <em>prio_all</em> with all CPUs.</p></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<div class="title">Note</div>
|
|
</td>
|
|
<td class="content">One may ask, why create a <em>prio_all</em> with all CPUs when that is
|
|
substantially the definition of the <em>root</em> cpuset? The answer is that it is
|
|
best to keep a separation between the <em>root</em> cpuset and everything else, even
|
|
if a particular cpuset duplicates <em>root</em> exactly. Usually, one builds
|
|
automation on top of a cpuset strategy. In these cases, it is best to avoid
|
|
using invariant names of cpusets, such as <em>root</em> for example, in this
|
|
automation.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="paragraph"><p>All of these <em>prio_*</em> cpusets can be created under root, in a flat way;
|
|
however, it is advantageous to create them as a hierarchy. The reasoning for
|
|
this is twofold: first, if a cpuset is destroyed, all its tasks are moved to
|
|
its parent; second, one can use exclusive CPUs in a hierarchy.</p></div>
|
|
<div class="paragraph"><p>There is a planned addition to the <code>proc</code> subcommand that will allow moving a
|
|
specified PIDSPEC of tasks running in a specified cpuset to its parent. This
|
|
addition will ease the automation burden.</p></div>
|
|
<div class="paragraph"><p>If a cpuset has CPUs that are exclusive to it, then other cpusets may not make
|
|
use of those CPUs unless they are children of that cpuset. This has more
|
|
relevance to machines with many CPUs and more complex strategies.</p></div>
|
|
<div class="paragraph"><p>Now, we start with a clean slate and build the appropriate cpusets as
|
|
follows.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -r
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
root 0-3 y 0 y 344 0 /
|
|
|
|
[zuul:cpuset-trunk]# cset set -c 0-3 prio_all
|
|
cset: --> created cpuset "prio_all"
|
|
|
|
[zuul:cpuset-trunk]# cset set -c 1-3 /prio_all/prio_high
|
|
cset: --> created cpuset "/prio_all/prio_high"
|
|
|
|
[zuul:cpuset-trunk]# cset set -c 2-3 /prio_all/prio_high/prio_med
|
|
cset: --> created cpuset "/prio_all/prio_high/prio_med"
|
|
|
|
[zuul:cpuset-trunk]# cset set -c 3 /prio_all/prio_high/prio_med/prio_low
|
|
cset: --> created cpuset "/prio_all/prio_high/prio_med/prio_low"
|
|
|
|
[zuul:cpuset-trunk]# cset set -c 0 system
|
|
cset: --> created cpuset "system"
|
|
|
|
[zuul:cpuset-trunk]# cset set -l -r
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
root 0-3 y 0 y 344 2 /
|
|
system 0 n 0 n 0 0 /system
|
|
prio_all 0-3 n 0 n 0 1 /prio_all
|
|
prio_high 1-3 n 0 n 0 1 /prio_all/prio_high
|
|
prio_med 2-3 n 0 n 0 1 /prio_all/prio_high/prio_med
|
|
prio_low 3 n 0 n 0 0 /prio_all/pr...rio_med/prio_low</code></pre>
|
|
</div></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<div class="title">Note</div>
|
|
</td>
|
|
<td class="content">We used the <code>-r/--recurse</code> switch to list all the sets in the last
|
|
command above. If we had not, then the <em>prio_med</em> and <em>prio_low</em> cpusets
|
|
would not have been listed.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="paragraph"><p>The strategy is now implemented and we now move all userspace tasks as well as
|
|
all movable kernel threads into the <em>system</em> cpuset to activate the shield.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset proc -m -k -f root -t system
|
|
cset: moving all tasks from root to /system
|
|
cset: moving 198 userspace tasks to /system
|
|
cset: moving 70 kernel threads to: /system
|
|
cset: --> not moving 76 threads (not unbound, use --force)
|
|
[==================================================]%
|
|
cset: done
|
|
|
|
[zuul:cpuset-trunk]# cset set -l -r
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
root 0-3 y 0 y 76 2 /
|
|
system 0 n 0 n 268 0 /system
|
|
prio_all 0-3 n 0 n 0 1 /prio_all
|
|
prio_high 1-3 n 0 n 0 1 /prio_all/prio_high
|
|
prio_med 2-3 n 0 n 0 1 /prio_all/prio_high/prio_med
|
|
prio_low 3 n 0 n 0 0 /prio_all/pr...rio_med/prio_low</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>The shield is now active. Since the <em>prio_*</em> cpuset names are unique, one can
|
|
assign tasks to them either via either their simple name, or their full path
|
|
(as described in the <code>proc</code> section above).</p></div>
|
|
<div class="paragraph"><p>You may have noted that there is an ellipsis in the path of the <em>prio_low</em>
|
|
cpuset in the listing above. This is done in order to fit the output onto an
|
|
80 character screen. If you want to see the entire line, then you need to use
|
|
the <code>-v/--verbose</code> flag as follows.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>[zuul:cpuset-trunk]# cset set -l -r -v
|
|
cset:
|
|
Name CPUs-X MEMs-X Tasks Subs Path
|
|
------------ ---------- - ------- - ----- ---- ----------
|
|
root 0-3 y 0 y 76 2 /
|
|
system 0 n 0 n 268 0 /system
|
|
prio_all 0-3 n 0 n 0 1 /prio_all
|
|
prio_high 1-3 n 0 n 0 1 /prio_all/prio_high
|
|
prio_med 2-3 n 0 n 0 1 /prio_all/prio_high/prio_med
|
|
prio_low 3 n 0 n 0 0 /prio_all/prio_high/prio_med/prio_low</code></pre>
|
|
</div></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div class="sect1">
|
|
<h2 id="_using_shortcuts">4. Using Shortcuts</h2>
|
|
<div class="sectionbody">
|
|
<div class="paragraph"><p>The commands listed in the previous sections always used all the required
|
|
options. <strong>Cset</strong> however does have a shortcut facility that will execute
|
|
certain commands without specifying all options. An effort has been made to
|
|
do this with the "principle of least surprise." This means that if you do not
|
|
specify options, but do specify parameters, then the outcome of the command
|
|
should be intuitive. As much as possible.</p></div>
|
|
<div class="paragraph"><p>Using shortcuts is of course not necessary. In fact, you can not only not use
|
|
shortcuts, but you can use long options instead of short, in case you really
|
|
enjoy typing… All kidding aside, using long options and not using shortcuts
|
|
does have a use case: when you write a script intended to be self-documenting,
|
|
or perhaps when you generate <strong>cset</strong> documentation.</p></div>
|
|
<div class="paragraph"><p>To begin, the subcommands <code>shield</code>, <code>set</code> and <code>proc</code> can themselves be
|
|
shortened to the fewest number of characters that are unambiguous. For
|
|
example, the following commands are identical:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code># cset shield -s -p 1234 <--> # cset sh -s -p 1234
|
|
# cset set -c 1,3 -s newset <--> # cset se -c 1,3 -s newset
|
|
# cset proc -s newset -e bash <--> # cset p -s newset -e bash</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Note that <code>proc</code> can be shortened to just <code>p</code>, while <code>shield</code> and <code>set</code> need
|
|
two letters to disambiguate.</p></div>
|
|
<div class="sect2">
|
|
<h3 id="_shield_subcommand_shortcuts">4.1. Shield Subcommand Shortcuts</h3>
|
|
<div class="paragraph"><p>The <code>shield</code> subcommand supports two areas with shortcuts: the case when there
|
|
is no options given where to <em>shield</em> is the common use case, and making the
|
|
<code>-p/--pid</code> option <em>optional</em> for the <code>-s/--shield</code> and <code>-u/--unshield</code>
|
|
options.</p></div>
|
|
<div class="paragraph"><p>For the common use case of actually <em>shielding</em> either a PIDSPEC or execing a
|
|
command into the shield, the following <strong>cset</strong> commands are equivalent.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code># cset shield -s -p 1234,500-649 <--> # cset sh 1234,500-649
|
|
# cset shield -s -e bash <--> # cset sh bash</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>When using the <code>-s</code> or <code>-u</code> shield/unshield options, it is optional to use the
|
|
<code>-p</code> option to specify a PIDSPEC. For example:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code># cset shield -s -p 1234 <--> # cset sh -s 1234
|
|
# cset shield -u -p 1234 <--> # cset sh -u 1234</code></pre>
|
|
</div></div>
|
|
</div>
|
|
<div class="sect2">
|
|
<h3 id="_set_subcommand_shortcuts">4.2. Set Subcommand Shortcuts</h3>
|
|
<div class="paragraph"><p>The <code>set</code> subcommand has a limited number of shortcuts. Basically, the
|
|
<code>-s/--set</code> option is optional in most cases and the <code>-l/--list</code> option is
|
|
also optional if you want to list sets. For example, these commands are
|
|
equivalent.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code># cset set -l -s myset <--> # cset se -l myset
|
|
# cset se -l myset <--> # cset se myset
|
|
|
|
# cset set -c 1,2,3 -s newset <--> # cset se -c 1,2,3 newset
|
|
# cset set -d -s newset <--> # cset se -d newset
|
|
|
|
# cset set -n newname -s oldname <--> # cset se -n newname oldname</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>In fact, if you want to apply either the list or the destroy options to
|
|
multiple cpusets with one <strong>cset</strong> command, you’ll need to not use the <code>-s</code>
|
|
option. For example:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code># cset se -d myset yourset ourset
|
|
--> destroys cpusets: myset, yourset and ourset
|
|
|
|
# cset se -l prio_high prio_med prio_low
|
|
--> lists only cpusets prio_high, prio_med and prio_low
|
|
--> the -l is optional in this case since list is default</code></pre>
|
|
</div></div>
|
|
</div>
|
|
<div class="sect2">
|
|
<h3 id="_proc_subcommand_shortcuts">4.3. Proc Subcommand Shortcuts</h3>
|
|
<div class="paragraph"><p>For the <code>proc</code> subcommand, the <code>-s</code>, <code>-t</code> and <code>-f</code> options to specify the
|
|
cpuset, the origination cpuset and the destination cpuset, can sometimes be
|
|
optional. For example, the following commands are equivalent.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>To list tasks in cpusets:
|
|
# cset proc -l -s myset \
|
|
# cset proc -l -f myset --> # cset p -l myset
|
|
# cset proc -l -t myset /
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# cset p -l myset <--> # cset p myset
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# cset proc -l -s one two <--> # cset p -l one two
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# cset p -l one two <--> # cset p one two
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To exec a process into a cpuset:
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# cset proc -s myset -e bash <--> # cset p myset -e bash</code></pre>
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</div></div>
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<div class="paragraph"><p>Movement of tasks into and out of cpusets have the following shortcuts.</p></div>
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<div class="listingblock">
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<div class="content">
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<pre><code>To move a PIDSPEC into a cpuset:
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# cset proc -m -p 4242,4243 -s myset <--> # cset p -m 4242,4243 myset
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# cset proc -m -p 12 -t myset <--> # cset p -m 12 myset
|
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|
To move all tasks from one cpuset to another:
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# cset proc -m -f set1 -t set2 \
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# cset proc -m -s set1 -t set2 --> # cset p -m set1 set2
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# cset proc -m -f set1 -s set2 /</code></pre>
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</div></div>
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</div>
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</div>
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</div>
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<div class="sect1">
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<h2 id="_what_to_do_if_there_are_problems">5. What To Do if There are Problems</h2>
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<div class="sectionbody">
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<div class="paragraph"><p>If you encounter problems with the <strong>cset</strong> application, the best option is to
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log a bug with the <strong>cset</strong> bugzilla instance found here:</p></div>
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<div class="literalblock">
|
|
<div class="content">
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<pre><code>https://github.com/lpechacek/cpuset/issues</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>If you are using <strong>cset</strong> on a supported operating system such as SLES or SLERT
|
|
from Novell, then please use that bugzilla instead at:</p></div>
|
|
<div class="literalblock">
|
|
<div class="content">
|
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<pre><code>https://bugzilla.suse.com</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>If the problem is repeatable, there is an excellent chance that it will get
|
|
fixed quickly. Also, <strong>cset</strong> contains a logging facility that is invaluable
|
|
for the developers to diagnose problems. To create a log of a run, use the
|
|
<code>-l/--log</code> option with a filename as an argument to the main <strong>cset</strong>
|
|
application. For example.</p></div>
|
|
<div class="listingblock">
|
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<div class="content">
|
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<pre><code># cset -l logfile.txt set -n newname oldname</code></pre>
|
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</div></div>
|
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<div class="paragraph"><p>That command saves a lot of debugging information in the <em>logfile.txt</em> file.
|
|
Please attach this file to the bug.</p></div>
|
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</div>
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</div>
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</div>
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<div id="footnotes"><hr /></div>
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<div id="footer">
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<div id="footer-text">
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Last updated 2015-12-23 14:00:13 CET
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