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From: James Courtier-Dutton <james.dutton@gmail.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	"Artem S. Tashkinov" <aros@gmx.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>, Michal Hocko <mhocko@kernel.org>
Subject: Re: Let's talk about the elephant in the room - the Linux kernel's inability to gracefully handle low memory pressure
Date: Tue, 6 Aug 2019 22:43:25 +0100	[thread overview]
Message-ID: <CAAMvbhEPcOw_kOVANSTUwPbNe2ebGL65ZEtyqdFhnwNMZ=NuVw@mail.gmail.com> (raw)
In-Reply-To: <CAJuCfpHhR+9ybt9ENzxMbdVUd_8rJN+zFbDm+5CeE2Desu82Gg@mail.gmail.com>

On Tue, 6 Aug 2019 at 02:09, Suren Baghdasaryan <surenb@google.com> wrote:
>
> 80% of the last 10 seconds spent in full stall would definitely be a
> problem. If the system was already low on memory (which it probably
> is, or we would not be reclaiming so hard and registering such a big
> stall) then oom-killer would probably kill something before 8 seconds
> are passed.

There are other things to consider also.
I can reproduce these types of symptoms and memory pressure is 100%
NOT the cause. (top showing 4GB of a 16GB system in use)
The cause as I see it is disk pressure and the lack of multiple queues
for disk IO requests.
For example, one process can hog 100% of the disk, without other
applications even being able to write just one sector.
We need a way for the linux kernel to better multiplex access to the
disk. Adding QOS, allowing interactive processes to interrupt long
background disk IO tasks.
If we could balance disk access across each active process, the user,
on their desktop, would think the system was more responsive.

Kind Regards

James

  parent reply	other threads:[~2019-08-06 21:44 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-04  9:23 Let's talk about the elephant in the room - the Linux kernel's inability to gracefully handle low memory pressure Artem S. Tashkinov
2019-08-05 12:13 ` Vlastimil Babka
2019-08-05 13:31   ` Michal Hocko
2019-08-05 16:47     ` Suren Baghdasaryan
2019-08-05 18:55     ` Johannes Weiner
2019-08-06  9:29       ` Michal Hocko
2019-08-05 19:31   ` Johannes Weiner
2019-08-06  1:08     ` Suren Baghdasaryan
2019-08-06  9:36       ` Vlastimil Babka
2019-08-06 14:27         ` Johannes Weiner
2019-08-06 14:36           ` Michal Hocko
2019-08-06 16:27             ` Suren Baghdasaryan
2019-08-06 22:01               ` Johannes Weiner
2019-08-07  7:59                 ` Michal Hocko
2019-08-07 20:51                   ` Johannes Weiner
2019-08-07 21:01                     ` Andrew Morton
2019-08-07 21:34                       ` Johannes Weiner
2019-08-07 21:12                     ` Johannes Weiner
2019-08-08 11:48                     ` Michal Hocko
2019-08-08 15:10                       ` ndrw.xf
2019-08-08 16:32                         ` Michal Hocko
2019-08-08 17:57                           ` ndrw.xf
2019-08-08 18:59                             ` Michal Hocko
2019-08-08 21:59                               ` ndrw
2019-08-09  8:57                                 ` Michal Hocko
2019-08-09 10:09                                   ` ndrw
2019-08-09 10:50                                     ` Michal Hocko
2019-08-09 14:18                                       ` Pintu Agarwal
2019-08-10 12:34                                       ` ndrw
2019-08-12  8:24                                         ` Michal Hocko
2019-08-10 21:07                                   ` ndrw
2021-07-24 17:32                         ` Alexey Avramov
2019-08-08 14:47                     ` Vlastimil Babka
2019-08-08 17:27                       ` Johannes Weiner
2019-08-09 14:56                         ` Vlastimil Babka
2019-08-09 17:31                           ` Johannes Weiner
2019-08-13 13:47                             ` Vlastimil Babka
2019-08-06 21:43       ` James Courtier-Dutton [this message]
2019-08-06 19:00 ` Florian Weimer
2019-08-20  6:46 ` Daniel Drake
2019-08-21 21:42   ` James Courtier-Dutton
2019-08-29 12:29     ` Michal Hocko
2019-09-02 20:15     ` Pavel Machek
2019-08-23  1:54   ` ndrw
2019-08-23  2:14     ` Daniel Drake
     [not found] <20190805090514.5992-1-hdanton@sina.com>
2019-08-05 12:01 ` Artem S. Tashkinov
2019-08-06  8:57 Johannes Buchner
2019-08-06 19:43 Remi Gauvin

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