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[209.85.220.65]) by mx.google.com with SMTPS id y9sor1026917ybh.81.2019.05.15.07.11.42 for (Google Transport Security); Wed, 15 May 2019 07:11:42 -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=diNffEIX; 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=DkABSB9+ocVSEDM1acJkspFNCkj7bZrir9llBRZBZbk=; b=diNffEIXfA/QFvQ4JDN4yWPbBFk9QYgBHQ4+BVJ1NfD0TF6g+5vVE0YSL1BnVjtejf CrAeQK4hrTmj1WQuMCeXacIymo+qMfuKsRMkXThtVIfdGWD3UWU68tOQie85EkAx3kZA YA78rnXPrmWhtTDNmjqohIlpLATlRKpAgbVUzdHZ/0oIWDRCWeJPe4MkeQfL4NNPlAhb 5gw18O/g48n/nZ7gRYd6s2xdXe7fCpmxbuVDtTd8Fhd7nK4blg8+HLxt6MmLicorJV+J ANLAPFx1lNLWprZ3HdLcTYYUg1gfx/xT6ADtn2L5nwfSQpvrZp2SEK2dbyUh8ZEYZ9Xq UKcQ== X-Google-Smtp-Source: APXvYqwFVrkJc6Ars41vZLv1PWwWvp79P7NNy1HRLGKPliMA4SZgci9iPnaAggH1BDGnbrEDsgGovH0KqGY39VpJ6TM= X-Received: by 2002:a25:4147:: with SMTP id o68mr20740148yba.148.1557929501573; Wed, 15 May 2019 07:11:41 -0700 (PDT) MIME-Version: 1.0 References: <20190514213940.2405198-1-guro@fb.com> <20190514213940.2405198-6-guro@fb.com> <0100016abbcb13b1-a1f70846-1d8c-4212-8e74-2b9be8c32ce7-000000@email.amazonses.com> In-Reply-To: <0100016abbcb13b1-a1f70846-1d8c-4212-8e74-2b9be8c32ce7-000000@email.amazonses.com> From: Shakeel Butt Date: Wed, 15 May 2019 07:11:30 -0700 Message-ID: Subject: Re: [PATCH v4 5/7] mm: rework non-root kmem_cache lifecycle management To: Christopher Lameter Cc: Roman Gushchin , Andrew Morton , Linux MM , LKML , Kernel Team , Johannes Weiner , Michal Hocko , Rik van Riel , Vladimir Davydov , Cgroups 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: From: Christopher Lameter Date: Wed, May 15, 2019 at 7:00 AM To: Roman Gushchin Cc: Andrew Morton, Shakeel Butt, , , , Johannes Weiner, Michal Hocko, Rik van Riel, Vladimir Davydov, > On Tue, 14 May 2019, Roman Gushchin wrote: > > > To make this possible we need to introduce a new percpu refcounter > > for non-root kmem_caches. The counter is initialized to the percpu > > mode, and is switched to atomic mode after deactivation, so we never > > shutdown an active cache. The counter is bumped for every charged page > > and also for every running allocation. So the kmem_cache can't > > be released unless all allocations complete. > > Increase refcounts during each allocation? Looks to be quite heavy > processing. Not really, it's a percpu refcnt. Basically the memcg's percpu_ref_tryget* is replaced with kmem_cache's percpu_ref_tryget, so, no additional processing.