Reduce realtime sched latency

Signed-off-by: Tyler Nijmeh <tylernij@gmail.com>

README.md

@@ -80,8 +80,8 @@ See RedHat: https://www.redhat.com/files/summit/session-assets/2018/Performance-
 ### kernel.sched_min_task_util_for_colocation: 35 --> 0
 This value determines when top-app tasks (which are of greater priority than background tasks) can be sched_boosted. Set this value to zero to allow top-app tasks to always be upmigrated if the sched_{up,down}migrate values are met.
 
-### kernel.sched_nr_migrate: 32 --> 128
-When migrating tasks between CPUs, allow the scheduler to migrate twice as many as usual. This should increase scheduling latency marginally, but increase the performance of SCHED_OTHER tasks. In testing, `cyclictest` reported a 2 microsecond increase in average latency, an a **decrease** in maximum latency of SCHED_FIFO tasks.
+### kernel.sched_nr_migrate: 32 --> 16
+Reduce the maximum number of sched entities that can migrate in a single scheduling period. Reducing this value reduces realtime task latency at the cost of SCHED_OTHER throughput.
 
 ### kernel.sched_schedstats: 1 --> 0
 Disable scheduler statistics accounting. This is just for debugging, but it adds overhead.

system/bin/ktweak

@@ -115,7 +115,7 @@ write /proc/sys/kernel/sched_min_granularity_ns 500000
 write /proc/sys/kernel/sched_wakeup_granularity_ns 1000000
 write /proc/sys/kernel/sched_migration_cost_ns 1000000
 write /proc/sys/kernel/sched_min_task_util_for_colocation 0
-write /proc/sys/kernel/sched_nr_migrate 128
+write /proc/sys/kernel/sched_nr_migrate 16
 write /proc/sys/kernel/sched_schedstats 0
 
 # VM