On Thu, Apr 05, 2018 at 01:55:16PM -0400, Johannes Weiner wrote: > From 4369ce161a9085aa408f2eca54f9de72909ee1b1 Mon Sep 17 00:00:00 2001 > From: Johannes Weiner <[email protected]> > Date: Thu, 5 Apr 2018 11:53:55 -0400 > Subject: [PATCH] mm: memcg: make sure memory.events is uptodate when waking > pollers > > a983b5ebee57 ("mm: memcontrol: fix excessive complexity in memory.stat > reporting") added per-cpu drift to all memory cgroup stats and events > shown in memory.stat and memory.events. > > For memory.stat this is acceptable. But memory.events issues file > notifications, and somebody polling the file for changes will be > confused when the counters in it are unchanged after a wakeup. > > Luckily, the events in memory.events - MEMCG_LOW, MEMCG_HIGH, > MEMCG_MAX, MEMCG_OOM - are sufficiently rare and high-level that we > don't need per-cpu buffering for them: MEMCG_HIGH and MEMCG_MAX would > be the most frequent, but they're counting invocations of reclaim, > which is a complex operation that touches many shared cachelines. > > This splits memory.events from the generic VM events and tracks them > in their own, unbuffered atomic counters. That's also cleaner, as it > eliminates the ugly enum nesting of VM and cgroup events. > > Fixes: a983b5ebee57 ("mm: memcontrol: fix excessive complexity in memory.stat > reporting") > Reported-by: Tejun Heo <[email protected]> > Signed-off-by: Johannes Weiner <[email protected]>
Yeah, that works. FWIW, Acked-by: Tejun Heo <[email protected]> Thanks. -- tejun
