linux-kernel - Re: [PATCH 2/2] memcg: periodically flush the memcg stats

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Message-ID: <YLogX+4YSMacgbGH@slm.duckdns.org>
Date:   Fri, 4 Jun 2021 08:45:19 -0400
From:   Tejun Heo <tj@...nel.org>
To:     Hillf Danton <hdanton@...a.com>
Cc:     Shakeel Butt <shakeelb@...gle.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Muchun Song <songmuchun@...edance.com>,
        Michal Hocko <mhocko@...nel.org>, Roman Gushchin <guro@...com>,
        Michal Koutný <mkoutny@...e.com>,
        Huang Ying <ying.huang@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        cgroups@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] memcg: periodically flush the memcg stats

On Fri, Jun 04, 2021 at 02:18:16PM +0800, Hillf Danton wrote:
> On Thu,  3 Jun 2021 18:56:40 -0700 Shakeel Butt wrote:
> >  
> > +static void flush_memcg_stats(struct work_struct *w)
> > +{
> > +	cgroup_rstat_flush(root_mem_cgroup->css.cgroup);
> > +	schedule_delayed_work(&stats_flush, round_jiffies(2UL*HZ));
> > +}
> 
> Given flush may block, the unbound wq is what you need.
>
> 	queue_delayed_work(system_unbound_wq, &stats_flush, 2 * HZ);

Default per-cpu workqueue can block just fine. I don't see a strong reason
why this would need to be unbound.

-- 
tejun