On 19.05.2017 19:34, Roman Guschin wrote:
2017-05-19 15:22 GMT+01:00 Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>:Show count of global oom killer invocations in /proc/vmstat and count of oom kills inside memory cgroup in knob "memory.events" (in memory.oom_control for v1 cgroup). Also describe difference between "oom" and "oom_kill" in memory cgroup documentation. Currently oom in memory cgroup kills tasks iff shortage has happened inside page fault. These counters helps in monitoring oom kills - for now the only way is grepping for magic words in kernel log. Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> --- Documentation/cgroup-v2.txt | 12 +++++++++++- include/linux/memcontrol.h | 1 + include/linux/vm_event_item.h | 1 + mm/memcontrol.c | 2 ++ mm/oom_kill.c | 6 ++++++ mm/vmstat.c | 1 + 6 files changed, 22 insertions(+), 1 deletion(-) diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt index dc5e2dcdbef4..a742008d76aa 100644 --- a/Documentation/cgroup-v2.txt +++ b/Documentation/cgroup-v2.txt @@ -830,9 +830,19 @@ PAGE_SIZE multiple when read back. oom + The number of time the cgroup's memory usage was + reached the limit and allocation was about to fail. + Result could be oom kill, -ENOMEM from any syscall or + completely ignored in cases like disk readahead. + For now oom in memory cgroup kills tasks iff shortage + has happened inside page fault.From a user's point of view the difference between "oom" and "max" becomes really vague here, assuming that "max" is described almost in the same words: "The number of times the cgroup's memory usage was about to go over the max boundary. If direct reclaim fails to bring it down, the OOM killer is invoked." I wonder, if it's better to fix the existing "oom" value to show what it has to show, according to docs, rather than to introduce a new one?
Nope, they are different. I think we should rephase documentation somehow low - count of reclaims below low level high - count of post-allocation reclaims above high level max - count of direct reclaims oom - count of failed direct reclaims oom_kill - count of oom killer invocations and killed processes
+ + oom_kill + The number of times the OOM killer has been invoked in the cgroup. This may not exactly match the number of - processes killed but should generally be close. + processes killed but should generally be close: each + invocation could kill several processes at once. memory.stat
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