Messages in this thread Patch in this message | | | Date | Mon, 13 Jan 2014 13:57:30 +0800 | From | Alex Shi <> | Subject | Re: [sched] 73628fba4: +69% context switches |
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On 01/11/2014 06:19 PM, Fengguang Wu wrote: > Alex, > > FYI, we find much increased interrupts and context switches introduced > by commit 73628fba4 ("sched: unify imbalance bias for target group") > in your noload branch:
Many thanks for the generous and quick testing! :)
few questions for the results and give a testing patch for try. it also push on github.
What's about the aim7 shell_rtns_1 and shared throughput? > > 7bea8c18805a5f1 73628fba451ae72221b155696 > --------------- ------------------------- > 14979 ~ 4% +1304.8% 210434 ~ 1% lkp-ne04/micro/aim7/shell_rtns_1 > 2748 ~ 5% +977.4% 29607 ~ 0% nhm-white/micro/aim7/shared > 17727 +1254.1% 240041 TOTAL interrupts.RES
RES interrupt increased about 200,000, but vmstat's interrupt increased a little. guess the vmstat data is per seconds, right? If so, it is better give how long time the vmstat running.
The same problem on the time.involuntary_context_switches and vmstat cs.
According to involuntary CS definition in time, RES interrupt will cause involuntary CS. but here 29607 RES of aim7/shared cause 233218 time inv CS, does sth I missed or the data is incorrect?
> > 7bea8c18805a5f1 73628fba451ae72221b155696 > --------------- ------------------------- > 3617 ~ 0% +69.2% 6118 ~ 0% lkp-ne04/micro/aim7/shell_rtns_1 > 3617 +69.2% 6118 TOTAL vmstat.system.in > > 7bea8c18805a5f1 73628fba451ae72221b155696 > --------------- ------------------------- > 132746 ~ 0% +69.0% 224346 ~ 1% lkp-ne04/micro/aim7/shell_rtns_1 > 220038 ~ 0% +6.0% 233218 ~ 0% nhm-white/micro/aim7/shared > 352785 +29.7% 457564 TOTAL time.involuntary_context_switches > > 7bea8c18805a5f1 73628fba451ae72221b155696 > --------------- ------------------------- > 1424581 ~ 0% +8.6% 1546786 ~ 0% lkp-ne04/micro/aim7/shell_rtns_1 > 1424581 +8.6% 1546786 TOTAL time.voluntary_context_switches > > 7bea8c18805a5f1 73628fba451ae72221b155696 > --------------- ------------------------- > 20982 ~ 0% +12.5% 23599 ~ 0% lkp-ne04/micro/aim7/shell_rtns_1 > 6005 ~ 0% +4.2% 6256 ~ 0% nhm-white/micro/aim7/shared > 26988 +10.6% 29856 TOTAL vmstat.system.cs > > vmstat.system.cs >
commit c5a8778a132cfa882609fbccb4ee6542eac9866d Author: Alex Shi <alex.shi@linaro.org> Date: Mon Jan 13 13:54:30 2014 +0800
more bias towards local cpu group
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 2b216ad..046ca2c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4008,7 +4008,6 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) struct task_group *tg; unsigned long weight; int balanced; - int bias = 100 + (sd->imbalance_pct -100) / 2; /* * If we wake multiple tasks be careful to not bounce @@ -4020,7 +4019,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) this_cpu = smp_processor_id(); prev_cpu = task_cpu(p); load = source_load(prev_cpu); - this_load = target_load(this_cpu, bias); + this_load = target_load(this_cpu, sd->imbalance_pct); /* * If sync wakeup then subtract the (maximum possible) @@ -4055,7 +4054,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) this_eff_load *= this_load + effective_load(tg, this_cpu, weight, weight); - prev_eff_load = bias; + prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2; prev_eff_load *= power_of(this_cpu); prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight); @@ -4100,7 +4099,6 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu) { struct sched_group *idlest = NULL, *group = sd->groups; unsigned long min_load = ULONG_MAX, this_load = 0; - int imbalance = 100 + (sd->imbalance_pct-100)/2; do { unsigned long load, avg_load; @@ -4123,7 +4121,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu) if (local_group) load = source_load(i); else - load = target_load(i, imbalance); + load = target_load(i, sd->imbalance_pct); avg_load += load; } -- Thanks Alex
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