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From: Michal Hocko <mhocko@kernel.org>
To: Tejun Heo <tj@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux MM <linux-mm@kvack.org>, Kernel Team <kernel-team@fb.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Chris Down <chris@chrisdown.name>,
	Cgroups <cgroups@vger.kernel.org>
Subject: Re: [PATCH 0/3] memcg: Slow down swap allocation as the available space gets depleted
Date: Mon, 20 Apr 2020 19:03:18 +0200	[thread overview]
Message-ID: <20200420170318.GV27314@dhcp22.suse.cz> (raw)
In-Reply-To: <20200420164740.GF43469@mtj.thefacebook.com>

On Mon 20-04-20 12:47:40, Tejun Heo wrote:
[...]
> > Coming back to this path series, to me, it seems like the patch series
> > is contrary to the vision you are presenting. Though the users are not
> > setting memory.[high|max] but they are setting swap.max and this
> > series is asking to set one more tunable i.e. swap.high. The approach
> > more consistent with the presented vision is to throttle or slow down
> > the allocators when the system swap is near full and there is no need
> > to set swap.max or swap.high.

I have the same impression as Shakeel here. The overall information we
have here is really scarce.
 
> It's a piece of the puzzle to make memory protection work comprehensively.
> You can argue that the fact swap isn't protection based is against the
> direction but I find that argument rather facetious as swap is quite
> different resource from memory and it's not like I'm saying limits shouldn't
> be used at all. There sure still are missing pieces - ie. slowing down on
> global depletion, but that doesn't mean swap.high isn't useful.

I have asked about the semantic of this know already and didn't really
get any real answer. So how does swap.high fit into high limit semantic
when it doesn't act as a limit. Considering that we cannot reclaim swap
space I find this really hard to grasp.

We definitely need more information here!
-- 
Michal Hocko
SUSE Labs


  reply	other threads:[~2020-04-20 17:03 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-17  1:06 Jakub Kicinski
2020-04-17  1:06 ` [PATCH 1/3] mm: prepare for swap over-high accounting and penalty calculation Jakub Kicinski
2020-04-17  1:06 ` [PATCH 2/3] mm: move penalty delay clamping out of calculate_high_delay() Jakub Kicinski
2020-04-17  1:06 ` [PATCH 3/3] mm: automatically penalize tasks with high swap use Jakub Kicinski
2020-04-17  7:37   ` Michal Hocko
2020-04-17 23:22     ` Jakub Kicinski
2020-04-17 16:11 ` [PATCH 0/3] memcg: Slow down swap allocation as the available space gets depleted Shakeel Butt
2020-04-17 16:23   ` Tejun Heo
2020-04-17 17:18     ` Shakeel Butt
2020-04-17 17:36       ` Tejun Heo
2020-04-17 17:51         ` Shakeel Butt
2020-04-17 19:35           ` Tejun Heo
2020-04-17 21:51             ` Shakeel Butt
2020-04-17 22:59               ` Tejun Heo
2020-04-20 16:12                 ` Shakeel Butt
2020-04-20 16:47                   ` Tejun Heo
2020-04-20 17:03                     ` Michal Hocko [this message]
2020-04-20 17:06                       ` Tejun Heo
2020-04-21 11:06                         ` Michal Hocko
2020-04-21 14:27                           ` Johannes Weiner
2020-04-21 16:11                             ` Michal Hocko
2020-04-21 16:56                               ` Johannes Weiner
2020-04-22 13:26                                 ` Michal Hocko
2020-04-22 14:15                                   ` Johannes Weiner
2020-04-22 15:43                                     ` Michal Hocko
2020-04-22 17:13                                       ` Johannes Weiner
2020-04-22 18:49                                         ` Michal Hocko
2020-04-23 15:00                                           ` Johannes Weiner
2020-04-24 15:05                                             ` Michal Hocko
2020-04-28 14:24                                               ` Johannes Weiner
2020-04-29  9:55                                                 ` Michal Hocko
2020-04-21 19:09                             ` Shakeel Butt
2020-04-21 21:59                               ` Johannes Weiner
2020-04-21 22:39                                 ` Shakeel Butt
2020-04-21 15:20                           ` Tejun Heo

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