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From: Chris Down <chris@chrisdown.name>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Michal Hocko <mhocko@suse.com>, Waiman Long <longman@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Ingo Molnar <mingo@kernel.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [RFC PATCH 0/8] memcg: Enable fine-grained per process memory control
Date: Mon, 7 Sep 2020 12:47:45 +0100	[thread overview]
Message-ID: <20200907114745.GA1076657@chrisdown.name> (raw)
In-Reply-To: <20200824165850.GA932571@cmpxchg.org>

Johannes Weiner writes:
>That all being said, the semantics of the new 'high' limit in cgroup2
>have allowed us to move reclaim/limit enforcement out of the
>allocation context and into the userspace return path.
>
>See the call to mem_cgroup_handle_over_high() from
>tracehook_notify_resume(), and the comments in try_charge() around
>set_notify_resume().
>
>This already solves the free->alloc ordering problem by allowing the
>allocation to exceed the limit temporarily until at least all locks
>are dropped, we know we can sleep etc., before performing enforcement.
>
>That means we may not need the timed sleeps anymore for that purpose,
>and could bring back directed waits for freeing-events again.
>
>What do you think? Any hazards around indefinite sleeps in that resume
>path? It's called before __rseq_handle_notify_resume and the
>arch-specific resume callback (which appears to be a no-op currently).
>
>Chris, Michal, what are your thoughts? It would certainly be simpler
>conceptually on the memcg side.

I'm not against that, although I personally don't feel very strongly about it 
either way, since the current behaviour clearly works in practice.

  reply	other threads:[~2020-09-07 11:52 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-17 14:08 [RFC PATCH 0/8] memcg: Enable fine-grained per process memory control Waiman Long
2020-08-17 14:08 ` [RFC PATCH 1/8] memcg: Enable fine-grained control of over memory.high action Waiman Long
2020-08-17 14:30   ` Chris Down
2020-08-17 15:38     ` Waiman Long
2020-08-17 16:11       ` Chris Down
2020-08-17 16:44   ` Shakeel Butt
2020-08-17 16:44     ` Shakeel Butt
2020-08-17 16:56     ` Chris Down
2020-08-18 19:12       ` Waiman Long
2020-08-18 19:14     ` Waiman Long
2020-08-17 14:08 ` [RFC PATCH 2/8] memcg, mm: Return ENOMEM or delay if memcg_over_limit Waiman Long
2020-08-17 14:08 ` [RFC PATCH 3/8] memcg: Allow the use of task RSS memory as over-high action trigger Waiman Long
2020-08-17 14:08   ` Waiman Long
2020-08-17 14:08 ` [RFC PATCH 4/8] fs/proc: Support a new procfs memctl file Waiman Long
2020-08-17 20:10   ` kernel test robot
2020-08-17 20:10   ` [RFC PATCH] fs/proc: proc_memctl_operations can be static kernel test robot
2020-08-17 14:08 ` [RFC PATCH 5/8] memcg: Allow direct per-task memory limit checking Waiman Long
2020-08-17 14:08 ` [RFC PATCH 6/8] memcg: Introduce additional memory control slowdown if needed Waiman Long
2020-08-17 14:08 ` [RFC PATCH 7/8] memcg: Enable logging of memory control mitigation action Waiman Long
2020-08-17 14:08   ` Waiman Long
2020-08-17 14:08 ` [RFC PATCH 8/8] memcg: Add over-high action prctl() documentation Waiman Long
2020-08-17 15:26 ` [RFC PATCH 0/8] memcg: Enable fine-grained per process memory control Michal Hocko
2020-08-17 15:55   ` Waiman Long
2020-08-17 15:55     ` Waiman Long
2020-08-17 19:26     ` Michal Hocko
2020-08-18 19:20       ` Waiman Long
2020-08-18 19:20         ` Waiman Long
2020-08-18  9:14 ` peterz
2020-08-18  9:14   ` peterz-wEGCiKHe2LqWVfeAwA7xHQ
2020-08-18  9:26   ` Michal Hocko
2020-08-18  9:26     ` Michal Hocko
2020-08-18  9:59     ` peterz
2020-08-18  9:59       ` peterz-wEGCiKHe2LqWVfeAwA7xHQ
2020-08-18 10:05       ` Michal Hocko
2020-08-18 10:18         ` peterz
2020-08-18 10:30           ` Michal Hocko
2020-08-18 10:36             ` peterz
2020-08-18 13:49           ` Johannes Weiner
2020-08-18 13:49             ` Johannes Weiner
2020-08-21 19:37             ` Peter Zijlstra
2020-08-21 19:37               ` Peter Zijlstra
2020-08-24 16:58               ` Johannes Weiner
2020-09-07 11:47                 ` Chris Down [this message]
2020-09-09 11:53                 ` Michal Hocko
2020-08-18 10:17       ` Chris Down
2020-08-18 10:17         ` Chris Down
2020-08-18 10:26         ` peterz
2020-08-18 10:35           ` Chris Down
2020-08-23  2:49         ` Waiman Long
2020-08-23  2:49           ` Waiman Long
2020-08-18  9:27   ` Chris Down
2020-08-18  9:27     ` Chris Down
2020-08-18 10:04     ` peterz
2020-08-18 12:55       ` Matthew Wilcox
2020-08-18 12:55         ` Matthew Wilcox
2020-08-20  6:11         ` Dave Chinner
2020-08-18 19:30     ` Waiman Long
2020-08-18 19:27   ` Waiman Long

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