diff options
| author | Olivier Cozette <olivier.cozette@arm.com> | 2012-10-17 14:30:30 +0100 |
|---|---|---|
| committer | Viresh Kumar <viresh.kumar@linaro.org> | 2013-03-12 15:17:53 +0530 |
| commit | 37380d0b7621d487b1d2885ad93227e880074ee5 (patch) | |
| tree | 4c6755d21c635dade14828b452ac4ac1d862948c /arch | |
| parent | 161bebe64ce4264105c09e022deeab0b94b06ead (diff) | |
ARM: Change load tracking scale using sysfs
These functions allow to change the load average period used
in the task load average computation through
/sys/kernel/hmp/load_avg_period_ms. This period is the time
in ms to go from 0 to 0.5 load average while running or the
time from 1 to 0.5 while sleeping.
The default one used is 32 and gives the same load_avg_ratio
computation than without this patch. These functions also allow
to change the up and down threshold of HMP using
/sys/kernel/hmp/{up,down}_threshold. Both must be between 0 and
1024. The thresholds are divided by 1024 before being compared
to the load_avg_ratio.
If /sys/kernel/hmp/load_avg_period_ms is 128 and
/sys/kernel/hmp/up_threshold is 512, a task will be migrated
to a bigger cluster after running for 128ms. Because after
load_avg_period_ms the load average is 0.5 and real up_threshold
us 512 / 1024 = 0.5.
Signed-off-by: Olivier Cozette <olivier.cozette@arm.com>
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/Kconfig | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 8ae87dc3806..42ea637002d 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1629,6 +1629,29 @@ config HMP_SLOW_CPU_MASK Specify the cpuids of the slow CPUs in the system as a list string, e.g. cpuid 0+1 should be specified as 0-1. +config HMP_VARIABLE_SCALE + bool "Allows changing the load tracking scale through sysfs" + depends on SCHED_HMP + help + When turned on, this option exports the thresholds and load average + period value for the load tracking patches through sysfs. + The values can be modified to change the rate of load accumulation + and the thresholds used for HMP migration. + The load_avg_period_ms is the time in ms to reach a load average of + 0.5 for an idle task of 0 load average ratio that start a busy loop. + The up_threshold and down_threshold is the value to go to a faster + CPU or to go back to a slower cpu. + The {up,down}_threshold are devided by 1024 before being compared + to the load average. + For examples, with load_avg_period_ms = 128 and up_threshold = 512, + a running task with a load of 0 will be migrated to a bigger CPU after + 128ms, because after 128ms its load_avg_ratio is 0.5 and the real + up_threshold is 0.5. + This patch has the same behavior as changing the Y of the load + average computation to + (1002/1024)^(LOAD_AVG_PERIOD/load_avg_period_ms) + but it remove intermadiate overflows in computation. + config HAVE_ARM_SCU bool help |