Re: [PATCH 8/8] mm: memcontrol: hook up vmpressure to socket pressure

Vladimir Davydov
2015-10-22T18:58:10Z

On Thu, Oct 22, 2015 at 12:21:36AM -0400, Johannes Weiner wrote:
...
> @@ -185,8 +183,29 @@ static void vmpressure_work_fn(struct work_struct *work)
> vmpr->reclaimed = 0;
> spin_unlock(&vmpr->sr_lock);
>
> + level = vmpressure_calc_level(scanned, reclaimed);
> +
> + if (level > VMPRESSURE_LOW) {

So we start socket_pressure at MEDIUM. Why not at LOW or CRITICAL?

> + struct mem_cgroup *memcg;
> + /*
> + * Let the socket buffer allocator know that we are
> + * having trouble reclaiming LRU pages.
> + *
> + * For hysteresis, keep the pressure state asserted
> + * for a second in which subsequent pressure events
> + * can occur.
> + *
> + * XXX: is vmpressure a global feature or part of
> + * memcg? There shouldn't be anything memcg-specific
> + * about exporting reclaim success ratios from the VM.
> + */
> + memcg = container_of(vmpr, struct mem_cgroup, vmpressure);
> + if (memcg != root_mem_cgroup)
> + memcg->socket_pressure = jiffies + HZ;

Why 1 second?

Thanks,
Vladimir

> + }
> +
> do {
> - if (vmpressure_event(vmpr, scanned, reclaimed))
> + if (vmpressure_event(vmpr, level))
> break;
> /*
> * If not handled, propagate the event upward into the