Re: [PATCH v2 6/7] sched: Add sched_overutilized tracepoint
From: Peter Zijlstra
Date: Mon May 13 2019 - 08:10:13 EST
On Fri, May 10, 2019 at 12:30:12PM +0100, Qais Yousef wrote:
> diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
> index cbcb47972232..0cf42d13d6c4 100644
> --- a/include/trace/events/sched.h
> +++ b/include/trace/events/sched.h
> @@ -600,6 +600,10 @@ DECLARE_TRACE(pelt_se,
> TP_PROTO(int cpu, const char *path, struct sched_entity *se),
> TP_ARGS(cpu, path, se));
>
> +DECLARE_TRACE(sched_overutilized,
> + TP_PROTO(int overutilized),
> + TP_ARGS(overutilized));
> +
> #endif /* _TRACE_SCHED_H */
>
> /* This part must be outside protection */
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 81036c34fd29..494032220fe7 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4965,8 +4965,10 @@ 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(1);
> + }
> }
> #else
> static inline void update_overutilized_status(struct rq *rq) { }
> @@ -8330,8 +8332,11 @@ 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(!!(sg_status & SG_OVERUTILIZED));
> } else if (sg_status & SG_OVERUTILIZED) {
> WRITE_ONCE(env->dst_rq->rd->overutilized, SG_OVERUTILIZED);
> + trace_sched_overutilized(1);
> }
> }
Note how the state is per root domain and the tracepoint doesn't
communicate that.