Messages in this thread | | | Date | Sat, 29 Apr 2023 16:58:29 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/1] sched: Consider CPU contention in frequency & load-balance busiest CPU selection |
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On Thu, Apr 06, 2023 at 05:50:30PM +0200, Dietmar Eggemann wrote: > Use new cpu_boosted_util_cfs() instead of cpu_util_cfs(). > > The former returns max(util_avg, runnable_avg) capped by max CPU > capacity. CPU contention is thereby considered through runnable_avg. > > The change in load-balance only affects migration type `migrate_util`.
But why, and how does it affect? That is, isn't this Changelog a wee bit sparse?
> Suggested-by: Vincent Guittot <vincent.guittot@linaro.org> > Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> > --- > kernel/sched/cpufreq_schedutil.c | 3 ++- > kernel/sched/fair.c | 2 +- > kernel/sched/sched.h | 19 +++++++++++++++++++ > 3 files changed, 22 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c > index e3211455b203..728b186cd367 100644 > --- a/kernel/sched/cpufreq_schedutil.c > +++ b/kernel/sched/cpufreq_schedutil.c > @@ -158,7 +158,8 @@ static void sugov_get_util(struct sugov_cpu *sg_cpu) > struct rq *rq = cpu_rq(sg_cpu->cpu); > > sg_cpu->bw_dl = cpu_bw_dl(rq); > - sg_cpu->util = effective_cpu_util(sg_cpu->cpu, cpu_util_cfs(sg_cpu->cpu), > + sg_cpu->util = effective_cpu_util(sg_cpu->cpu, > + cpu_boosted_util_cfs(sg_cpu->cpu), > FREQUENCY_UTIL, NULL); > } > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index bc358dc4faeb..5ae36224a1c2 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -10481,7 +10481,7 @@ static struct rq *find_busiest_queue(struct lb_env *env, > break; > > case migrate_util: > - util = cpu_util_cfs(i); > + util = cpu_boosted_util_cfs(i); > > /* > * Don't try to pull utilization from a CPU with one > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index 060616944d7a..f42c859579d9 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -2994,6 +2994,25 @@ static inline unsigned long cpu_util_cfs(int cpu) > return min(util, capacity_orig_of(cpu)); > } > > +/* > + * cpu_boosted_util_cfs() - Estimates the amount of CPU capacity used by > + * CFS tasks. > + * > + * Similar to cpu_util_cfs() but also take possible CPU contention into > + * consideration. > + */ > +static inline unsigned long cpu_boosted_util_cfs(int cpu) > +{ > + unsigned long runnable; > + struct cfs_rq *cfs_rq; > + > + cfs_rq = &cpu_rq(cpu)->cfs; > + runnable = READ_ONCE(cfs_rq->avg.runnable_avg); > + runnable = min(runnable, capacity_orig_of(cpu)); > + > + return max(cpu_util_cfs(cpu), runnable); > +} > + > static inline unsigned long cpu_util_rt(struct rq *rq) > { > return READ_ONCE(rq->avg_rt.util_avg); > -- > 2.25.1 >
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