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From: Tejun Heo <tj@kernel.org>
To: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Roman Gushchin <guro@fb.com>,
	linux-mm@kvack.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org, kernel-team@fb.com,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] mm: memcontrol: asynchronous reclaim for memory.high
Date: Thu, 20 Feb 2020 15:54:16 -0500	[thread overview]
Message-ID: <20200220205416.GI698990@mtj.thefacebook.com> (raw)
In-Reply-To: <20200220195535.7xblt45akld6eftj@ca-dmjordan1.us.oracle.com>

Hello, Daniel.

On Thu, Feb 20, 2020 at 02:55:35PM -0500, Daniel Jordan wrote:
> On Thu, Feb 20, 2020 at 01:45:45PM -0500, Tejun Heo wrote:
> > The setup cost can be lazy optimized but it'd still have to bounce the
> > tiny pieces of work to different threads instead of processing them in
> > one fell swoop from the same context, which most likely is gonna be
> > untenably expensive.
> 
> I see, your last mail is clearer now.  If it's easy to do, a pointer to where
> this happens would help so we're on the same page.

Network packet rx is the clearest example I think, but you already
mentioned it. Reclaim is less so but when kswapd reclaims, it walks
everybody, and there can be a lot of small cgroups.

Thanks.

-- 
tejun

WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Daniel Jordan <daniel.m.jordan-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
	Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	kernel-team-b10kYP2dOMg@public.gmane.org,
	Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Subject: Re: [PATCH] mm: memcontrol: asynchronous reclaim for memory.high
Date: Thu, 20 Feb 2020 15:54:16 -0500	[thread overview]
Message-ID: <20200220205416.GI698990@mtj.thefacebook.com> (raw)
In-Reply-To: <20200220195535.7xblt45akld6eftj-S51bK0XF4qpuJJETbFA3a0B3C2bhBk7L0E9HWUfgJXw@public.gmane.org>

Hello, Daniel.

On Thu, Feb 20, 2020 at 02:55:35PM -0500, Daniel Jordan wrote:
> On Thu, Feb 20, 2020 at 01:45:45PM -0500, Tejun Heo wrote:
> > The setup cost can be lazy optimized but it'd still have to bounce the
> > tiny pieces of work to different threads instead of processing them in
> > one fell swoop from the same context, which most likely is gonna be
> > untenably expensive.
> 
> I see, your last mail is clearer now.  If it's easy to do, a pointer to where
> this happens would help so we're on the same page.

Network packet rx is the clearest example I think, but you already
mentioned it. Reclaim is less so but when kswapd reclaims, it walks
everybody, and there can be a lot of small cgroups.

Thanks.

-- 
tejun

  reply	other threads:[~2020-02-20 20:54 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-19 18:12 [PATCH] mm: memcontrol: asynchronous reclaim for memory.high Johannes Weiner
2020-02-19 18:12 ` Johannes Weiner
2020-02-19 18:37 ` Michal Hocko
2020-02-19 18:37   ` Michal Hocko
2020-02-19 19:16   ` Johannes Weiner
2020-02-19 19:16     ` Johannes Weiner
2020-02-19 19:53     ` Michal Hocko
2020-02-19 19:53       ` Michal Hocko
2020-02-19 21:17       ` Johannes Weiner
2020-02-20  9:46         ` Michal Hocko
2020-02-20  9:46           ` Michal Hocko
2020-02-20 14:41           ` Johannes Weiner
2020-02-20 14:41             ` Johannes Weiner
2020-02-19 21:41       ` Daniel Jordan
2020-02-19 21:41         ` Daniel Jordan
2020-02-19 22:08         ` Johannes Weiner
2020-02-19 22:08           ` Johannes Weiner
2020-02-20 15:45           ` Daniel Jordan
2020-02-20 15:45             ` Daniel Jordan
2020-02-20 15:56             ` Tejun Heo
2020-02-20 15:56               ` Tejun Heo
2020-02-20 18:23               ` Daniel Jordan
2020-02-20 18:23                 ` Daniel Jordan
2020-02-20 18:45                 ` Tejun Heo
2020-02-20 18:45                   ` Tejun Heo
2020-02-20 19:55                   ` Daniel Jordan
2020-02-20 19:55                     ` Daniel Jordan
2020-02-20 20:54                     ` Tejun Heo [this message]
2020-02-20 20:54                       ` Tejun Heo
2020-02-19 19:17   ` Chris Down
2020-02-19 19:17     ` Chris Down
2020-02-19 19:31   ` Andrew Morton
2020-02-19 19:31     ` Andrew Morton
2020-02-19 21:33     ` Johannes Weiner
2020-02-26 20:25 ` Shakeel Butt
2020-02-26 20:25   ` Shakeel Butt
2020-02-26 20:25   ` Shakeel Butt
2020-02-26 22:26   ` Johannes Weiner
2020-02-26 22:26     ` Johannes Weiner
2020-02-26 23:36     ` Shakeel Butt
2020-02-26 23:36       ` Shakeel Butt
2020-02-26 23:36       ` Shakeel Butt
2020-02-26 23:46       ` Johannes Weiner
2020-02-27  0:12     ` Yang Shi
2020-02-27  0:12       ` Yang Shi
2020-02-27  2:42       ` Shakeel Butt
2020-02-27  2:42         ` Shakeel Butt
2020-02-27  2:42         ` Shakeel Butt
2020-02-27  9:58       ` Michal Hocko
2020-02-27  9:58         ` Michal Hocko
2020-02-27 12:50       ` Johannes Weiner
2020-02-27 12:50         ` Johannes Weiner
2020-02-26 23:59   ` Yang Shi
2020-02-26 23:59     ` Yang Shi
2020-02-27  2:36     ` Shakeel Butt
2020-02-27  2:36       ` Shakeel Butt

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