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From: Michal Hocko <mhocko@kernel.org>
To: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Chris Down <chris@chrisdown.name>,
	Andrew Morton <akpm@linux-foundation.org>,
	Roman Gushchin <guro@fb.com>, Dennis Zhou <dennis@kernel.org>,
	linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
	linux-mm@kvack.org, kernel-team@fb.com
Subject: Re: [PATCH 2/2] mm: Consider subtrees in memory.events
Date: Tue, 29 Jan 2019 15:43:06 +0100	[thread overview]
Message-ID: <20190129144306.GO18811@dhcp22.suse.cz> (raw)
In-Reply-To: <20190128174905.GU50184@devbig004.ftw2.facebook.com>

On Mon 28-01-19 09:49:05, Tejun Heo wrote:
> Hello, Michal.
> 
> On Mon, Jan 28, 2019 at 06:05:26PM +0100, Michal Hocko wrote:
> > Yeah, that is quite clear. But it also assumes that the hierarchy is
> > pretty stable but cgroups might go away at any time. I am not saying
> > that the aggregated events are not useful I am just saying that it is
> > quite non-trivial to use and catch all potential corner cases. Maybe I
> 
> It really isn't complicated and doesn't require stable subtree.
> 
> > am overcomplicating it but one thing is quite clear to me. The existing
> > semantic is really useful to watch for the reclaim behavior at the
> > current level of the tree. You really do not have to care what is
> > happening in the subtree when it is clear that the workload itself
> > is underprovisioned etc. Considering that such a semantic already
> > existis, somebody might depend on it and we likely want also aggregated
> > semantic then I really do not see why to risk regressions rather than
> > add a new memory.hierarchy_events and have both.
> 
> The problem then is that most other things are hierarchical including
> some fields in .events files, so if we try to add local stats and
> events, there's no good way to add them.

All memcg events are represented non-hierarchical AFAICS
memcg_memory_event() simply accounts at the level when it happens. Or do
I miss something? Or are you talking about .events files for other
controllers?
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2019-01-29 14:43 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-23 22:31 [PATCH 2/2] mm: Consider subtrees in memory.events Chris Down
2019-01-24  0:24 ` Roman Gushchin
2019-01-24  1:03   ` Chris Down
2019-01-24  8:22 ` Michal Hocko
2019-01-24 15:21   ` Tejun Heo
2019-01-24 15:51     ` Michal Hocko
2019-01-24 16:00   ` Johannes Weiner
2019-01-24 17:01     ` Michal Hocko
2019-01-24 18:23       ` Johannes Weiner
2019-01-25  8:42         ` Michal Hocko
2019-01-25 16:51           ` Tejun Heo
2019-01-25 17:37             ` Michal Hocko
2019-01-25 17:37               ` Michal Hocko
2019-01-25 18:28               ` Tejun Heo
2019-01-28 12:51                 ` Michal Hocko
2019-01-28 14:28                   ` Tejun Heo
2019-01-28 14:52                     ` Michal Hocko
2019-01-28 14:54                       ` Tejun Heo
2019-01-28 15:18                         ` Michal Hocko
2019-01-28 15:41                           ` Tejun Heo
2019-01-28 17:05                             ` Michal Hocko
2019-01-28 17:49                               ` Tejun Heo
2019-01-29 14:43                                 ` Michal Hocko [this message]
2019-01-29 14:52                                   ` Tejun Heo
2019-01-30 16:50                                     ` Michal Hocko
2019-01-30 17:06                                       ` Tejun Heo
2019-01-30 17:41                                         ` Michal Hocko
2019-01-30 17:52                                           ` Tejun Heo
2019-01-30 18:16                                             ` Michal Hocko
2019-01-30 19:11                                         ` Shakeel Butt
2019-01-30 19:11                                           ` Shakeel Butt
2019-01-30 19:27                                           ` Johannes Weiner
2019-01-30 19:30                                             ` Johannes Weiner
2019-01-30 19:37                                               ` Shakeel Butt
2019-01-30 19:37                                                 ` Shakeel Butt
2019-01-30 19:23                   ` Johannes Weiner
2019-01-30 20:05                     ` Michal Hocko
2019-01-30 21:31                       ` Johannes Weiner
2019-01-31  8:58                         ` Michal Hocko
2019-01-31 16:22                           ` Johannes Weiner
2019-02-01 10:27                             ` Michal Hocko
2019-02-01 16:34                               ` Johannes Weiner
2019-01-28 15:59                 ` Shakeel Butt
2019-01-28 15:59                   ` Shakeel Butt
2019-01-28 16:05                   ` Tejun Heo
2019-01-28 16:08                     ` Shakeel Butt
2019-01-28 16:08                       ` Shakeel Butt
2019-01-28 16:12                       ` Tejun Heo
2019-01-28 14:30 ` Tejun Heo
2019-02-08 22:43 ` [PATCH v2 1/2] mm: Rename ambiguously named memory.stat counters and functions Chris Down
2019-02-08 22:44   ` [PATCH v2 2/2] mm: Consider subtrees in memory.events Chris Down
2019-02-11 19:01     ` Johannes Weiner
2019-02-11 18:55   ` [PATCH v2 1/2] mm: Rename ambiguously named memory.stat counters and functions Johannes Weiner

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