On Fri, Dec 01, 2017 at 06:01:57PM +0000, Brendan Jackman wrote:
> @@ -7913,6 +7928,29 @@ static inline void update_sd_lb_stats(struct lb_env
> *env, struct sd_lb_stats *sd
> if (child && child->flags & SD_PREFER_SIBLING)
> prefer_sibling = 1;
>
> +#ifdef CONFIG_NO_HZ_COMMON
> + if (env->idle == CPU_NEWLY_IDLE) {
> + int cpu;
> +
> + /* Update the stats of NOHZ idle CPUs in the sd */
> + for_each_cpu_and(cpu, sched_domain_span(env->sd),
> + nohz.idle_cpus_mask) {
> + struct rq *rq = cpu_rq(cpu);
> +
> + /* ... Unless we've already done since the last tick */
> + if (time_after(jiffies,
> rq->last_blocked_load_update_tick))
> + update_blocked_averages(cpu);
> + }
> + }
> + /*
> + * If we've just updated all of the NOHZ idle CPUs, then we can push
> + * back the next nohz.next_update, which will prevent an unnecessary
> + * wakeup for the nohz stats kick
> + */
> + if (cpumask_subset(nohz.idle_cpus_mask, sched_domain_span(env->sd)))
> + nohz.next_update = jiffies + LOAD_AVG_PERIOD;
> +#endif
> +
> load_idx = get_sd_load_idx(env->sd, env->idle);
>
> do {
We're already going to be iterating all those CPUs through
update_sg_lb_stats(), why not push it all the way down there and avoid
the double iteration?
