From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2AC2FC2D0A3 for ; Wed, 4 Nov 2020 08:39:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7954A2074B for ; Wed, 4 Nov 2020 08:39:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="m0Cd64um" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7954A2074B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A80006B0036; Wed, 4 Nov 2020 03:39:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A334B6B005D; Wed, 4 Nov 2020 03:39:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 96FBA6B0068; Wed, 4 Nov 2020 03:39:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0155.hostedemail.com [216.40.44.155]) by kanga.kvack.org (Postfix) with ESMTP id 6BED26B0036 for ; Wed, 4 Nov 2020 03:39:56 -0500 (EST) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 0A2F48249980 for ; Wed, 4 Nov 2020 08:39:56 +0000 (UTC) X-FDA: 77446087992.07.beef88_2f05137272bf Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin07.hostedemail.com (Postfix) with ESMTP id E1C891803F9A9 for ; Wed, 4 Nov 2020 08:39:55 +0000 (UTC) X-HE-Tag: beef88_2f05137272bf X-Filterd-Recvd-Size: 6598 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf33.hostedemail.com (Postfix) with ESMTP for ; Wed, 4 Nov 2020 08:39:55 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1604479194; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=syUOeZVis/mCwu8fd3UHVg+xOCzGMKG+bwd8HAGySfQ=; b=m0Cd64umG8ekm2e4xzXb1VdFG7hZa8TCyBpftGpns6wGN0PMRrsJ0NBX4AmlpaVZLIv3OH NLIWU7sciCIMKrmJWSv+rlmbktjWLPEYtEkk6UYrfeOIuk2qNdziQdGRnGZBx/bzp48hD+ EYx+lARTS7an1MOFV//1Hfuy5GjM76g= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id AAEA3AC2E; Wed, 4 Nov 2020 08:39:54 +0000 (UTC) Date: Wed, 4 Nov 2020 09:39:53 +0100 From: Michal Hocko To: Roman Gushchin Cc: linux-mm@kvack.org, Andrew Morton , Shakeel Butt , Johannes Weiner , Tejun Heo , linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH rfc 2/3] docs: cgroup-v1: reflect the deprecation of the non-hierarchical mode Message-ID: <20201104083953.GD10052@dhcp22.suse.cz> References: <20201103212725.3716088-1-guro@fb.com> <20201103212725.3716088-3-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201103212725.3716088-3-guro@fb.com> 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 Tue 03-11-20 13:27:24, Roman Gushchin wrote: > Update cgroup v1 docs after the deprecation of the non-hierarchical > mode of the memory controller. > > Signed-off-by: Roman Gushchin Acked-by: Michal Hocko > --- > .../admin-guide/cgroup-v1/memcg_test.rst | 8 ++-- > .../admin-guide/cgroup-v1/memory.rst | 40 ++++++------------- > 2 files changed, 16 insertions(+), 32 deletions(-) > > diff --git a/Documentation/admin-guide/cgroup-v1/memcg_test.rst b/Documentation/admin-guide/cgroup-v1/memcg_test.rst > index 3f7115e07b5d..4f83de2dab6e 100644 > --- a/Documentation/admin-guide/cgroup-v1/memcg_test.rst > +++ b/Documentation/admin-guide/cgroup-v1/memcg_test.rst > @@ -219,13 +219,11 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y. > > This is an easy way to test page migration, too. > > -9.5 mkdir/rmdir > ---------------- > +9.5 nested cgroups > +------------------ > > - When using hierarchy, mkdir/rmdir test should be done. > - Use tests like the following:: > + Use tests like the following for testing nested cgroups:: > > - echo 1 >/opt/cgroup/01/memory/use_hierarchy > mkdir /opt/cgroup/01/child_a > mkdir /opt/cgroup/01/child_b > > diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst > index 12757e63b26c..a44cd467d218 100644 > --- a/Documentation/admin-guide/cgroup-v1/memory.rst > +++ b/Documentation/admin-guide/cgroup-v1/memory.rst > @@ -77,6 +77,8 @@ Brief summary of control files. > memory.soft_limit_in_bytes set/show soft limit of memory usage > memory.stat show various statistics > memory.use_hierarchy set/show hierarchical account enabled > + This knob is deprecated and shouldn't be > + used. > memory.force_empty trigger forced page reclaim > memory.pressure_level set memory pressure notifications > memory.swappiness set/show swappiness parameter of vmscan > @@ -495,16 +497,13 @@ cgroup might have some charge associated with it, even though all > tasks have migrated away from it. (because we charge against pages, not > against tasks.) > > -We move the stats to root (if use_hierarchy==0) or parent (if > -use_hierarchy==1), and no change on the charge except uncharging > +We move the stats to parent, and no change on the charge except uncharging > from the child. > > Charges recorded in swap information is not updated at removal of cgroup. > Recorded information is discarded and a cgroup which uses swap (swapcache) > will be charged as a new owner of it. > > -About use_hierarchy, see Section 6. > - > 5. Misc. interfaces > =================== > > @@ -527,8 +526,6 @@ About use_hierarchy, see Section 6. > write will still return success. In this case, it is expected that > memory.kmem.usage_in_bytes == memory.usage_in_bytes. > > - About use_hierarchy, see Section 6. > - > 5.2 stat file > ------------- > > @@ -675,31 +672,20 @@ hierarchy:: > d e > > In the diagram above, with hierarchical accounting enabled, all memory > -usage of e, is accounted to its ancestors up until the root (i.e, c and root), > -that has memory.use_hierarchy enabled. If one of the ancestors goes over its > -limit, the reclaim algorithm reclaims from the tasks in the ancestor and the > -children of the ancestor. > - > -6.1 Enabling hierarchical accounting and reclaim > ------------------------------------------------- > - > -A memory cgroup by default disables the hierarchy feature. Support > -can be enabled by writing 1 to memory.use_hierarchy file of the root cgroup:: > +usage of e, is accounted to its ancestors up until the root (i.e, c and root). > +If one of the ancestors goes over its limit, the reclaim algorithm reclaims > +from the tasks in the ancestor and the children of the ancestor. > > - # echo 1 > memory.use_hierarchy > - > -The feature can be disabled by:: > +6.1 Hierarchical accounting and reclaim > +--------------------------------------- > > - # echo 0 > memory.use_hierarchy > +Hierarchical accounting is enabled by default. Disabling the hierarchical > +accounting is deprecated. An attempt to do it will result in a failure > +and a warning printed to dmesg. > > -NOTE1: > - Enabling/disabling will fail if either the cgroup already has other > - cgroups created below it, or if the parent cgroup has use_hierarchy > - enabled. > +For compatibility reasons writing 1 to memory.use_hierarchy will always pass:: > > -NOTE2: > - When panic_on_oom is set to "2", the whole system will panic in > - case of an OOM event in any cgroup. > + # echo 1 > memory.use_hierarchy > > 7. Soft limits > ============== > -- > 2.26.2 -- Michal Hocko SUSE Labs