Messages in this thread |  | | From | Joel Fernandes <> | Date | Wed, 24 Jan 2018 08:40:07 -0800 | Subject | Re: [PATCH v3 1/3] sched/fair: add util_est on top of PELT |
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On Tue, Jan 23, 2018 at 10:08 AM, Patrick Bellasi <patrick.bellasi@arm.com> wrote: > The util_avg signal computed by PELT is too variable for some use-cases. > For example, a big task waking up after a long sleep period will have its > utilization almost completely decayed. This introduces some latency before > schedutil will be able to pick the best frequency to run a task. [...] > -static inline unsigned long task_util(struct task_struct *p); > static unsigned long cpu_util_wake(int cpu, struct task_struct *p); > > static unsigned long capacity_spare_wake(int cpu, struct task_struct *p) > @@ -6262,6 +6337,11 @@ static inline unsigned long task_util(struct task_struct *p) > return p->se.avg.util_avg; > } > > +static inline unsigned long task_util_est(struct task_struct *p) > +{ > + return max(p->se.avg.util_est.ewma, p->se.avg.util_est.last); > +} > + > /* > * cpu_util_wake: Compute cpu utilization with any contributions from > * the waking task p removed. > diff --git a/kernel/sched/features.h b/kernel/sched/features.h > index 9552fd5854bf..c459a4b61544 100644 > --- a/kernel/sched/features.h > +++ b/kernel/sched/features.h > @@ -85,3 +85,8 @@ SCHED_FEAT(ATTACH_AGE_LOAD, true) > SCHED_FEAT(WA_IDLE, true) > SCHED_FEAT(WA_WEIGHT, true) > SCHED_FEAT(WA_BIAS, true) > + > +/* > + * UtilEstimation. Use estimated CPU utilization. > + */ > +SCHED_FEAT(UTIL_EST, false) > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index 2e95505e23c6..0b4d9750a927 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -470,6 +470,7 @@ struct cfs_rq { > * CFS load tracking > */ > struct sched_avg avg; > + unsigned long util_est_runnable;
Since struct sched_avg would now have util_est, cfs_rq gets it too. Then can we not try to reuse that struct and avoid having to expand cfs_rq more than needed?
I went through previous conversations and couldn't find a reason, if I missed something I appreciate if you can explain the rationale.
thanks,
- Joel
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