1. 02 6月, 2019 1 次提交
    • C
      mm, memcg: consider subtrees in memory.events · 9852ae3f
      Chris Down 提交于
      memory.stat and other files already consider subtrees in their output, and
      we should too in order to not present an inconsistent interface.
      
      The current situation is fairly confusing, because people interacting with
      cgroups expect hierarchical behaviour in the vein of memory.stat,
      cgroup.events, and other files.  For example, this causes confusion when
      debugging reclaim events under low, as currently these always read "0" at
      non-leaf memcg nodes, which frequently causes people to misdiagnose breach
      behaviour.  The same confusion applies to other counters in this file when
      debugging issues.
      
      Aggregation is done at write time instead of at read-time since these
      counters aren't hot (unlike memory.stat which is per-page, so it does it
      at read time), and it makes sense to bundle this with the file
      notifications.
      
      After this patch, events are propagated up the hierarchy:
      
          [root@ktst ~]# cat /sys/fs/cgroup/system.slice/memory.events
          low 0
          high 0
          max 0
          oom 0
          oom_kill 0
          [root@ktst ~]# systemd-run -p MemoryMax=1 true
          Running as unit: run-r251162a189fb4562b9dabfdc9b0422f5.service
          [root@ktst ~]# cat /sys/fs/cgroup/system.slice/memory.events
          low 0
          high 0
          max 7
          oom 1
          oom_kill 1
      
      As this is a change in behaviour, this can be reverted to the old
      behaviour by mounting with the `memory_localevents' flag set.  However, we
      use the new behaviour by default as there's a lack of evidence that there
      are any current users of memory.events that would find this change
      undesirable.
      
      akpm: this is a behaviour change, so Cc:stable.  THis is so that
      forthcoming distros which use cgroup v2 are more likely to pick up the
      revised behaviour.
      
      Link: http://lkml.kernel.org/r/20190208224419.GA24772@chrisdown.nameSigned-off-by: NChris Down <chris@chrisdown.name>
      Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: NShakeel Butt <shakeelb@google.com>
      Cc: Michal Hocko <mhocko@kernel.org>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Roman Gushchin <guro@fb.com>
      Cc: Dennis Zhou <dennis@kernel.org>
      Cc: Suren Baghdasaryan <surenb@google.com>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9852ae3f
  2. 31 5月, 2019 26 次提交
  3. 26 5月, 2019 1 次提交
  4. 24 5月, 2019 12 次提交
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