Messages in this thread | | | From | Vincent Guittot <> | Date | Fri, 21 Jul 2023 11:57:19 +0200 | Subject | Re: [PATCH v3 2/3] sched/uclamp: Ignore (util == 0) optimization in feec() when p_util_max = 0 |
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On Mon, 17 Jul 2023 at 23:57, Qais Yousef <qyousef@layalina.io> wrote: > > find_energy_efficient_cpu() bails out early if effective util of the > task is 0 as the delta at this point will be zero and there's nothing > for EAS to do. When uclamp is being used, this could lead to wrong > decisions when uclamp_max is set to 0. In this case the task is capped > to performance point 0, but it is actually running and consuming energy > and we can benefit from EAS energy calculations. > > Rework the condition so that it bails out for when util is actually 0 or > uclamp_min is requesting a higher performance point. > > We can do that without needing to use uclamp_task_util(); remove it. > > Fixes: d81304bc6193 ("sched/uclamp: Cater for uclamp in find_energy_efficient_cpu()'s early exit condition") > Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
> --- > kernel/sched/fair.c | 18 +----------------- > 1 file changed, 1 insertion(+), 17 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index d489eece5a0d..c701f490ca4c 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -4348,22 +4348,6 @@ static inline unsigned long task_util_est(struct task_struct *p) > return max(task_util(p), _task_util_est(p)); > } > > -#ifdef CONFIG_UCLAMP_TASK > -static inline unsigned long uclamp_task_util(struct task_struct *p, > - unsigned long uclamp_min, > - unsigned long uclamp_max) > -{ > - return clamp(task_util_est(p), uclamp_min, uclamp_max); > -} > -#else > -static inline unsigned long uclamp_task_util(struct task_struct *p, > - unsigned long uclamp_min, > - unsigned long uclamp_max) > -{ > - return task_util_est(p); > -} > -#endif > - > static inline void util_est_enqueue(struct cfs_rq *cfs_rq, > struct task_struct *p) > { > @@ -7588,7 +7572,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) > target = prev_cpu; > > sync_entity_load_avg(&p->se); > - if (!uclamp_task_util(p, p_util_min, p_util_max)) > + if (!task_util_est(p) && p_util_min == 0) > goto unlock; > > eenv_task_busy_time(&eenv, p, prev_cpu); > -- > 2.25.1 >
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