From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id B12FC6B0311 for ; Wed, 26 Jul 2017 09:28:15 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id r7so31842095wrb.0 for ; Wed, 26 Jul 2017 06:28:15 -0700 (PDT) Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com. [67.231.153.30]) by mx.google.com with ESMTPS id w20si13404448wrc.519.2017.07.26.06.28.14 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 Jul 2017 06:28:14 -0700 (PDT) From: Roman Gushchin Subject: [v4 4/4] mm, oom, docs: describe the cgroup-aware OOM killer Date: Wed, 26 Jul 2017 14:27:18 +0100 Message-ID: <20170726132718.14806-5-guro@fb.com> In-Reply-To: <20170726132718.14806-1-guro@fb.com> References: <20170726132718.14806-1-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Roman Gushchin , Michal Hocko , Vladimir Davydov , Johannes Weiner , Tetsuo Handa , David Rientjes , Tejun Heo , kernel-team@fb.com, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Update cgroups v2 docs. Signed-off-by: Roman Gushchin Cc: Michal Hocko Cc: Vladimir Davydov Cc: Johannes Weiner Cc: Tetsuo Handa Cc: David Rientjes Cc: Tejun Heo Cc: kernel-team@fb.com Cc: cgroups@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org --- Documentation/cgroup-v2.txt | 62 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt index cb9ea281ab72..bf106b6b6b52 100644 --- a/Documentation/cgroup-v2.txt +++ b/Documentation/cgroup-v2.txt @@ -48,6 +48,7 @@ v1 is available under Documentation/cgroup-v1/. 5-2-1. Memory Interface Files 5-2-2. Usage Guidelines 5-2-3. Memory Ownership + 5-2-4. Cgroup-aware OOM Killer 5-3. IO 5-3-1. IO Interface Files 5-3-2. Writeback @@ -1001,6 +1002,37 @@ PAGE_SIZE multiple when read back. high limit is used and monitored properly, this limit's utility is limited to providing the final safety net. + memory.oom_kill_all_tasks + + A read-write single value file which exits on non-root + cgroups. The default is "0". + + Defines whether the OOM killer should treat the cgroup + as a single entity during the victim selection. + + If set, OOM killer will kill all belonging tasks in + corresponding cgroup is selected as an OOM victim. + + Be default, OOM killer respect /proc/pid/oom_score_adj value + -1000, and will never kill the task, unless oom_kill_all_tasks + is set. + + memory.oom_priority + + A read-write single value file which exits on non-root + cgroups. The default is "0". + + An integer number within the [-10000, 10000] range, + which defines the order in which the OOM killer selects victim + memory cgroups. + + OOM killer prefers memory cgroups with larger priority if they + are populated with elegible tasks. + + The oom_priority value is compared within sibling cgroups. + + The root cgroup has the oom_priority 0, which cannot be changed. + memory.events A read-only flat-keyed file which exists on non-root cgroups. The following entries are defined. Unless specified @@ -1205,6 +1237,36 @@ POSIX_FADV_DONTNEED to relinquish the ownership of memory areas belonging to the affected files to ensure correct memory ownership. +Cgroup-aware OOM Killer +~~~~~~~~~~~~~~~~~~~~~~~ + +Cgroup v2 memory controller implements a cgroup-aware OOM killer. +It means that it treats memory cgroups as first class OOM entities. + +Under OOM conditions the memory controller tries to make the best +choise of a victim, hierarchically looking for the largest memory +consumer. By default, it will look for the biggest task in the +biggest leaf cgroup. + +Be default, all cgroups have oom_priority 0, and OOM killer will +chose the largest cgroup recursively on each level. For non-root +cgroups it's possible to change the oom_priority, and it will cause +the OOM killer to look athe the priority value first, and compare +sizes only of cgroups with equal priority. + +But a user can change this behavior by enabling the per-cgroup +oom_kill_all_tasks option. If set, it causes the OOM killer treat +the whole cgroup as an indivisible memory consumer. In case if it's +selected as on OOM victim, all belonging tasks will be killed. + +Tasks in the root cgroup are treated as independent memory consumers, +and are compared with other memory consumers (e.g. leaf cgroups). +The root cgroup doesn't support the oom_kill_all_tasks feature. + +This affects both system- and cgroup-wide OOMs. For a cgroup-wide OOM +the memory controller considers only cgroups belonging to the sub-tree +of the OOM'ing cgroup. + IO -- -- 2.13.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org