From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f199.google.com (mail-pf1-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id D9DCE8E0038 for ; Wed, 9 Jan 2019 14:18:50 -0500 (EST) Received: by mail-pf1-f199.google.com with SMTP id u20so5947638pfa.1 for ; Wed, 09 Jan 2019 11:18:50 -0800 (PST) Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com. [115.124.30.132]) by mx.google.com with ESMTPS id p14si5220131pfi.12.2019.01.09.11.18.48 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 09 Jan 2019 11:18:49 -0800 (PST) From: Yang Shi Subject: [v3 PATCH 1/5] doc: memcontrol: fix the obsolete content about force empty Date: Thu, 10 Jan 2019 03:14:41 +0800 Message-Id: <1547061285-100329-2-git-send-email-yang.shi@linux.alibaba.com> In-Reply-To: <1547061285-100329-1-git-send-email-yang.shi@linux.alibaba.com> References: <1547061285-100329-1-git-send-email-yang.shi@linux.alibaba.com> Sender: owner-linux-mm@kvack.org List-ID: To: mhocko@suse.com, hannes@cmpxchg.org, shakeelb@google.com, akpm@linux-foundation.org Cc: yang.shi@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org We don't do page cache reparent anymore when offlining memcg, so update force empty related content accordingly. Reviewed-by: Shakeel Butt Acked-by: Michal Hocko Cc: Johannes Weiner Signed-off-by: Yang Shi --- Documentation/cgroup-v1/memory.txt | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/Documentation/cgroup-v1/memory.txt b/Documentation/cgroup-v1/memory.txt index 3682e99..8e2cb1d 100644 --- a/Documentation/cgroup-v1/memory.txt +++ b/Documentation/cgroup-v1/memory.txt @@ -70,7 +70,7 @@ 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 - memory.force_empty # trigger forced move charge to parent + memory.force_empty # trigger forced page reclaim memory.pressure_level # set memory pressure notifications memory.swappiness # set/show swappiness parameter of vmscan (See sysctl's vm.swappiness) @@ -459,8 +459,9 @@ About use_hierarchy, see Section 6. the cgroup will be reclaimed and as many pages reclaimed as possible. The typical use case for this interface is before calling rmdir(). - Because rmdir() moves all pages to parent, some out-of-use page caches can be - moved to the parent. If you want to avoid that, force_empty will be useful. + Though rmdir() offlines memcg, but the memcg may still stay there due to + charged file caches. Some out-of-use page caches may keep charged until + memory pressure happens. If you want to avoid that, force_empty will be useful. Also, note that when memory.kmem.limit_in_bytes is set the charges due to kernel pages will still be seen. This is not considered a failure and the -- 1.8.3.1