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ktweak/ktweak

209 lines
5.8 KiB
Bash

#!/usr/bin/env bash
# Written by Draco (tytydraco @ GitHub)
# The name of the current branch for logging purposes
BRANCH="balance"
# Maximum unsigned integer size in C
UINT_MAX="4294967295"
# Duration in nanoseconds of one scheduling period
SCHED_PERIOD="$((4 * 1000 * 1000))"
# How many tasks should we have at a maximum in one scheduling period
SCHED_TASKS="8"
write() {
# Bail out if file does not exist
[[ ! -f "$1" ]] && return 1
# Make file writable in case it is not already
chmod +w "$1" 2> /dev/null
# Write the new value and bail if there's an error
if ! echo "$2" > "$1" 2> /dev/null
then
echo "Failed: $1$2"
return 1
fi
# Log the success
echo "$1$2"
}
# Check for root permissions and bail if not granted
if [[ "$(id -u)" -ne 0 ]]
then
echo "No root permissions. Exiting."
exit 1
fi
# Detect if we are running on Android
grep -q android /proc/cmdline && ANDROID=true
# Log the date and time for records sake
echo "Time of execution: $(date)"
echo "Branch: $BRANCH"
# Sync to data in the rare case a device crashes
sync
# Limit max perf event processing time to this much CPU usage
write /proc/sys/kernel/perf_cpu_time_max_percent 5
# Group tasks for less stutter but less throughput
write /proc/sys/kernel/sched_autogroup_enabled 1
# Execute child process before parent after fork
write /proc/sys/kernel/sched_child_runs_first 1
# Preliminary requirement for the following values
write /proc/sys/kernel/sched_tunable_scaling 0
# Reduce the maximum scheduling period for lower latency
write /proc/sys/kernel/sched_latency_ns "$SCHED_PERIOD"
# Schedule this ratio of tasks in the guarenteed sched period
write /proc/sys/kernel/sched_min_granularity_ns "$((SCHED_PERIOD / SCHED_TASKS))"
# Require preeptive tasks to surpass half of a sched period in vmruntime
write /proc/sys/kernel/sched_wakeup_granularity_ns "$((SCHED_PERIOD / 2))"
# Reduce the frequency of task migrations
write /proc/sys/kernel/sched_migration_cost_ns 5000000
# Always allow sched boosting on top-app tasks
[[ "$ANDROID" == true ]] && write /proc/sys/kernel/sched_min_task_util_for_colocation 0
# Improve real time latencies by reducing the scheduler migration time
write /proc/sys/kernel/sched_nr_migrate 32
# Disable scheduler statistics to reduce overhead
write /proc/sys/kernel/sched_schedstats 0
# Disable unnecessary printk logging
write /proc/sys/kernel/printk_devkmsg off
# Start non-blocking writeback later
write /proc/sys/vm/dirty_background_ratio 10
# Start blocking writeback later
write /proc/sys/vm/dirty_ratio 30
# Require dirty memory to stay in memory for longer
write /proc/sys/vm/dirty_expire_centisecs 3000
# Run the dirty memory flusher threads less often
write /proc/sys/vm/dirty_writeback_centisecs 3000
# Disable read-ahead for swap devices
write /proc/sys/vm/page-cluster 0
# Update /proc/stat less often to reduce jitter
write /proc/sys/vm/stat_interval 10
# Swap to the swap device at a fair rate
write /proc/sys/vm/swappiness 100
# Fairly prioritize page cache and file structures
write /proc/sys/vm/vfs_cache_pressure 100
# Enable Explicit Congestion Control
write /proc/sys/net/ipv4/tcp_ecn 1
# Enable fast socket open for receiver and sender
write /proc/sys/net/ipv4/tcp_fastopen 3
# Disable SYN cookies
write /proc/sys/net/ipv4/tcp_syncookies 0
if [[ -f "/sys/kernel/debug/sched_features" ]]
then
# Consider scheduling tasks that are eager to run
write /sys/kernel/debug/sched_features NEXT_BUDDY
# Schedule tasks on their origin CPU if possible
write /sys/kernel/debug/sched_features TTWU_QUEUE
fi
[[ "$ANDROID" == true ]] && if [[ -d "/dev/stune/" ]]
then
# We are not concerned with prioritizing latency
write /dev/stune/top-app/schedtune.prefer_idle 0
# Mark top-app as boosted, find high-performing CPUs
write /dev/stune/top-app/schedtune.boost 1
fi
# Loop over each CPU in the system
for cpu in /sys/devices/system/cpu/cpu*/cpufreq
do
# Fetch the available governors from the CPU
avail_govs="$(cat "$cpu/scaling_available_governors")"
# Attempt to set the governor in this order
for governor in schedutil interactive
do
# Once a matching governor is found, set it and break for this CPU
if [[ "$avail_govs" == *"$governor"* ]]
then
write "$cpu/scaling_governor" "$governor"
break
fi
done
done
# Apply governor specific tunables for schedutil
find /sys/devices/system/cpu/ -name schedutil -type d | while IFS= read -r governor
do
# Consider changing frequencies once per scheduling period
write "$governor/up_rate_limit_us" "$((SCHED_PERIOD / 1000))"
write "$governor/down_rate_limit_us" "$((4 * SCHED_PERIOD / 1000))"
write "$governor/rate_limit_us" "$((SCHED_PERIOD / 1000))"
# Jump to hispeed frequency at this load percentage
write "$governor/hispeed_load" 90
write "$governor/hispeed_freq" "$UINT_MAX"
done
# Apply governor specific tunables for interactive
find /sys/devices/system/cpu/ -name interactive -type d | while IFS= read -r governor
do
# Consider changing frequencies once per scheduling period
write "$governor/timer_rate" "$((SCHED_PERIOD / 1000))"
write "$governor/min_sample_time" "$((SCHED_PERIOD / 1000))"
# Jump to hispeed frequency at this load percentage
write "$governor/go_hispeed_load" 90
write "$governor/hispeed_freq" "$UINT_MAX"
done
for queue in /sys/block/*/queue
do
# Choose the first governor available
avail_scheds="$(cat "$queue/scheduler")"
for sched in cfq noop kyber bfq mq-deadline none
do
if [[ "$avail_scheds" == *"$sched"* ]]
then
write "$queue/scheduler" "$sched"
break
fi
done
# Do not use I/O as a source of randomness
write "$queue/add_random" 0
# Disable I/O statistics accounting
write "$queue/iostats" 0
# Reduce heuristic read-ahead in exchange for I/O latency
write "$queue/read_ahead_kb" 128
# Reduce the maximum number of I/O requests in exchange for latency
write "$queue/nr_requests" 64
done
# Always return success, even if the last write fails
exit 0