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[209.132.183.28]) by mx.google.com with ESMTPS id x62si11204467vkg.89.2019.07.23.07.30.13 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Jul 2019 07:30:13 -0700 (PDT) Received-SPF: pass (google.com: domain of longman@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of longman@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=longman@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3914781F18; Tue, 23 Jul 2019 14:30:11 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-160.bos.redhat.com [10.18.17.160]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1EBAC600D1; Tue, 23 Jul 2019 14:30:08 +0000 (UTC) Subject: Re: [PATCH] mm, slab: Extend slab/shrink to shrink all the memcg caches To: peter enderborg , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Alexander Viro , Jonathan Corbet , Luis Chamberlain , Kees Cook , Johannes Weiner , Michal Hocko , Vladimir Davydov Cc: linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Roman Gushchin , Shakeel Butt , Andrea Arcangeli References: <20190702183730.14461-1-longman@redhat.com> <71ab6307-9484-fdd3-fe6d-d261acf7c4a5@sony.com> From: Waiman Long Organization: Red Hat Message-ID: Date: Tue, 23 Jul 2019 10:30:07 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <71ab6307-9484-fdd3-fe6d-d261acf7c4a5@sony.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Tue, 23 Jul 2019 14:30:12 +0000 (UTC) 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 7/22/19 8:46 AM, peter enderborg wrote: > On 7/2/19 8:37 PM, Waiman Long wrote: >> Currently, a value of '1" is written to /sys/kernel/slab//shrink >> file to shrink the slab by flushing all the per-cpu slabs and free >> slabs in partial lists. This applies only to the root caches, though. >> >> Extends this capability by shrinking all the child memcg caches and >> the root cache when a value of '2' is written to the shrink sysfs file. >> >> On a 4-socket 112-core 224-thread x86-64 system after a parallel kernel >> build, the the amount of memory occupied by slabs before shrinking >> slabs were: >> >> # grep task_struct /proc/slabinfo >> task_struct 7114 7296 7744 4 8 : tunables 0 0 >> 0 : slabdata 1824 1824 0 >> # grep "^S[lRU]" /proc/meminfo >> Slab: 1310444 kB >> SReclaimable: 377604 kB >> SUnreclaim: 932840 kB >> >> After shrinking slabs: >> >> # grep "^S[lRU]" /proc/meminfo >> Slab: 695652 kB >> SReclaimable: 322796 kB >> SUnreclaim: 372856 kB >> # grep task_struct /proc/slabinfo >> task_struct 2262 2572 7744 4 8 : tunables 0 0 >> 0 : slabdata 643 643 0 > > What is the time between this measurement points? Should not the shrinked memory show up as reclaimable? In this case, I echoed '2' to all the shrink sysfs files under /sys/kernel/slab. The purpose of shrinking caches is to reclaim as much unused memory slabs from all the caches, irrespective if they are reclaimable or not. We do not reclaim any used objects. That is why we see the numbers were reduced in both cases. Cheers, Longman