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[209.85.220.65]) by mx.google.com with SMTPS id t11sor2760930ybp.132.2019.04.19.14.14.41 for (Google Transport Security); Fri, 19 Apr 2019 14:14:41 -0700 (PDT) Received-SPF: pass (google.com: domain of shakeelb@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=TN+lD0Yx; spf=pass (google.com: domain of shakeelb@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=shakeelb@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Ep33f62HX3AzUBDcVwFjTp0Z/qGrzWSSxgy6irC3Dwc=; b=TN+lD0YxK8/Z39tQFNeng7o7MdFoxCJhCMdqBA3VkWcQCiVs/XYz7qebhQCkvh98UL QYtk4dk9C4miikKW7ebUyVThbhx3xOBfed7dosNc80MVG1HOVIEDJwbCgFx4BBOxXmuZ 9BJC9skhYCCPRcDFlVoAk1wWJi5QPd3x7bV9nZrQOdhbYWEdfxh+qFEzSbhjh2zcF+Qk nEUxMY1lIEric7Sr22cPqLby1FKEYg8H2b/hKJaehzG2Bhsi5DI8SaX8kUlMXuKmwFZp 2fucI4cAXY9cXKu/jqmNdiuJqUHmBHXRYYAbiFf+Wwhsg2U7d7P+0QNi3h2mwT28yPuy 9j6Q== X-Google-Smtp-Source: APXvYqwP8W9joct14TvJoGQu1QeSZbbs3jHQ7fURiorHFky435pvPWJhgSP+s96y780vcjdoFGt8mEO4Ajd7ZHl7V9g= X-Received: by 2002:a25:4147:: with SMTP id o68mr5056203yba.148.1555708480546; Fri, 19 Apr 2019 14:14:40 -0700 (PDT) MIME-Version: 1.0 References: <20190418214224.61900-1-shakeelb@google.com> <20190419200733.GB31878@tower.DHCP.thefacebook.com> In-Reply-To: <20190419200733.GB31878@tower.DHCP.thefacebook.com> From: Shakeel Butt Date: Fri, 19 Apr 2019 14:14:29 -0700 Message-ID: Subject: Re: [PATCH] memcg: refill_stock for kmem uncharging too To: Roman Gushchin Cc: Johannes Weiner , Vladimir Davydov , Michal Hocko , Andrew Morton , "linux-mm@kvack.org" , "cgroups@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Apr 19, 2019 at 1:07 PM Roman Gushchin wrote: > > On Thu, Apr 18, 2019 at 02:42:24PM -0700, Shakeel Butt wrote: > > The commit 475d0487a2ad ("mm: memcontrol: use per-cpu stocks for socket > > memory uncharging") added refill_stock() for skmem uncharging path to > > optimize workloads having high network traffic. Do the same for the kmem > > uncharging as well. However bypass the refill for offlined memcgs to not > > cause zombie apocalypse. > > > > Signed-off-by: Shakeel Butt > > Hello, Shakeel! > > > --- > > mm/memcontrol.c | 17 ++++++++--------- > > 1 file changed, 8 insertions(+), 9 deletions(-) > > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 2535e54e7989..7b8de091f572 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -178,6 +178,7 @@ struct mem_cgroup_event { > > > > static void mem_cgroup_threshold(struct mem_cgroup *memcg); > > static void mem_cgroup_oom_notify(struct mem_cgroup *memcg); > > +static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages); > > > > /* Stuffs for move charges at task migration. */ > > /* > > @@ -2097,10 +2098,7 @@ static void drain_stock(struct memcg_stock_pcp *stock) > > struct mem_cgroup *old = stock->cached; > > > > if (stock->nr_pages) { > > - page_counter_uncharge(&old->memory, stock->nr_pages); > > - if (do_memsw_account()) > > - page_counter_uncharge(&old->memsw, stock->nr_pages); > > - css_put_many(&old->css, stock->nr_pages); > > + cancel_charge(old, stock->nr_pages); > > stock->nr_pages = 0; > > } > > stock->cached = NULL; > > @@ -2133,6 +2131,11 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) > > struct memcg_stock_pcp *stock; > > unsigned long flags; > > > > + if (unlikely(!mem_cgroup_online(memcg))) { > > + cancel_charge(memcg, nr_pages); > > + return; > > + } > > I'm slightly concerned about this part. Do we really need it? > The number of "zombies" which we can pin is limited by the number of CPUs, > and it will drop fast if there is any load on the machine. > > If we skip offline memcgs, it can slow down charging/uncharging of skmem, > which might be a problem, if the socket is in active use by an other cgroup. > Honestly, I'd drop this part. > Sure, I will wait for comments from others and then send the v2 without this. Shakeel