From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Gushchin Subject: [v6 4/4] mm, oom, docs: describe the cgroup-aware OOM killer Date: Wed, 23 Aug 2017 17:52:01 +0100 Message-ID: <20170823165201.24086-5-guro@fb.com> References: <20170823165201.24086-1-guro@fb.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=facebook; bh=5kKEH5YHBfdFNRdu2jEcs2X8uExcewckBFKkir99S6A=; b=AvwoM4s7JM2DzHhvq45HHv/UAU1y6npx+1vbJBF71NXLzkHZV5EWJ0qvhFE1BirYz+N4 mtPuWi7JJroDvYcirnP3b57gUVbplLk77A/5gNfKqBzDh0p6UsJvSuPy5avcqqwr8aPe wd5gdR/1zWCJCxgi5Oqenbi7Rp5b/sxRSAQ= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.onmicrosoft.com; s=selector1-fb-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version; bh=5kKEH5YHBfdFNRdu2jEcs2X8uExcewckBFKkir99S6A=; b=ZzBIh1pYbvQ9Y8vmna4PezZRM0JxtbealaX0l8ytd1wMZJPBWejkwbpYSBf33jm0nhqkYgok2+lIzx3Ug/YqHKh07SK3V53QUoPwth/C/n/z7FzZ+MiR9KwmwELL6jcjdRjnZ/3bTCwKWEvA60duzaQNuuqnghC++/X704eL6RM= In-Reply-To: <20170823165201.24086-1-guro@fb.com> Sender: owner-linux-mm@kvack.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 dec5afdaa36d..79ac407bf5a0 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. OOM Killer 5-3. IO 5-3-1. IO Interface Files 5-3-2. Writeback @@ -1002,6 +1003,34 @@ 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 + + A read-write single value file which exists on non-root + cgroups. The default is "0". + + If set, OOM killer will kill all processes attached to the cgroup + if selected as an OOM victim. + + Be default, the OOM killer respects the /proc/pid/oom_score_adj + value -1000, and will never kill the task, unless oom_kill_all + is set. + + memory.oom_priority + + A read-write single value file which exists 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 eligible 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 @@ -1206,6 +1235,39 @@ POSIX_FADV_DONTNEED to relinquish the ownership of memory areas belonging to the affected files to ensure correct memory ownership. +OOM Killer +~~~~~~~~~~~~~~~~~~~~~~~ + +Cgroup v2 memory controller implements a cgroup-aware OOM killer. +It means that it treats cgroups as first class OOM entities. + +Under OOM conditions the memory controller tries to make the best +choice of a victim, hierarchically looking for the largest memory +consumer. By default, it will look for the biggest task in the +biggest leaf memory cgroup. + +By default, all memory cgroups have oom_priority 0, and OOM killer +will choice the cgroup with the largest memory consuption 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 +at the priority value first, and compare sizes only of memory +cgroups with equal priority. + +A user can change this behavior by enabling the per-cgroup +oom_kill_all option. If set, OOM killer will kill all processes +attached to the cgroup if selected as an OOM victim. + +Tasks in the root cgroup are treated as independent memory consumers, +and are compared with other memory consumers (leaf memory cgroups). +The root cgroup doesn't support the oom_kill_all 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. + +If there are no cgroups with the enabled memory controller, +the OOM killer is using the "traditional" process-based approach. + IO -- -- 2.13.5 -- 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