Messages in this thread | | | Date | Mon, 17 Jun 2019 17:50:10 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 5/6] sched: Add sched_overutilized tracepoint |
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On Tue, Jun 04, 2019 at 12:14:58PM +0100, Qais Yousef wrote: > The new tracepoint allows us to track the changes in overutilized > status. > > Overutilized status is associated with EAS. It indicates that the system > is in high performance state. EAS is disabled when the system is in this > state since there's not much energy savings while high performance tasks > are pushing the system to the limit and it's better to default to the > spreading behavior of the scheduler. > > This tracepoint helps understanding and debugging the conditions under > which this happens. > > Signed-off-by: Qais Yousef <qais.yousef@arm.com> > --- > include/trace/events/sched.h | 4 ++++ > kernel/sched/fair.c | 11 +++++++++-- > 2 files changed, 13 insertions(+), 2 deletions(-) > > diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h > index c7dd9bc7f001..edd96e04049f 100644 > --- a/include/trace/events/sched.h > +++ b/include/trace/events/sched.h > @@ -621,6 +621,10 @@ DECLARE_TRACE(pelt_se_tp, > TP_PROTO(struct sched_entity *se), > TP_ARGS(se)); > > +DECLARE_TRACE(sched_overutilized_tp, > + TP_PROTO(int overutilized, struct root_domain *rd), > + TP_ARGS(overutilized, rd)); > +
strictly speaking you only need @rd :-)
> #endif /* _TRACE_SCHED_H */ > > /* This part must be outside protection */ > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 8e0015ebf109..e2418741608e 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -5179,8 +5179,10 @@ static inline bool cpu_overutilized(int cpu) > > static inline void update_overutilized_status(struct rq *rq) > { > - if (!READ_ONCE(rq->rd->overutilized) && cpu_overutilized(rq->cpu)) > + if (!READ_ONCE(rq->rd->overutilized) && cpu_overutilized(rq->cpu)) { > WRITE_ONCE(rq->rd->overutilized, SG_OVERUTILIZED); > + trace_sched_overutilized_tp(1, rq->rd); > + } > } > #else > static inline void update_overutilized_status(struct rq *rq) { } > @@ -8542,8 +8544,13 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd > > /* Update over-utilization (tipping point, U >= 0) indicator */ > WRITE_ONCE(rd->overutilized, sg_status & SG_OVERUTILIZED); > + > + trace_sched_overutilized_tp(!!(sg_status & SG_OVERUTILIZED), rd); > } else if (sg_status & SG_OVERUTILIZED) { > - WRITE_ONCE(env->dst_rq->rd->overutilized, SG_OVERUTILIZED); > + struct root_domain *rd = env->dst_rq->rd; > + > + WRITE_ONCE(rd->overutilized, SG_OVERUTILIZED); > + trace_sched_overutilized_tp(1, rd); > } > }
But I figure since we need both values anyway, this isn't too much of a bother.
I'm going to flip the argument order though.
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