From: Michal Hocko <mhocko@kernel.org>
To: Alkis Georgopoulos <alkisg@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, bugzilla-daemon@bugzilla.kernel.org,
Mel Gorman <mgorman@techsingularity.net>,
Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [Bug 196157] New: 100+ times slower disk writes on 4.x+/i386/16+RAM, compared to 3.x
Date: Mon, 26 Jun 2017 07:46:24 +0200 [thread overview]
Message-ID: <20170626054623.GC31972@dhcp22.suse.cz> (raw)
In-Reply-To: <a373c35d-7d83-973c-126e-a08c411115cb@gmail.com>
On Mon 26-06-17 08:28:07, Alkis Georgopoulos wrote:
> IGBPI?I1I? 23/06/2017 02:38 I 1/4 I 1/4 , I? Michal Hocko I-I3I?I+-I?Iu:
> >this means that the highmem is not dirtyable and so only 20% of the free
> >lowmem (+ page cache in that region) is considered and writers might
> >get throttled quite early (this might be a really low number when the
> >lowmem is congested already). Do you see the same problem when enabling
> >highmem_is_dirtyable = 1?
> >
>
> Excellent advice! :)
> Indeed, setting highmem_is_dirtyable=1 completely eliminates the issue!
>
> Is that something that should be =1 by default,
Unfortunatelly, this is not something that can be applied in general.
This can lead to a premature OOM killer invocations. E.g. a direct write
to the block device cannot use highmem, yet there won't be anything to
throttle those writes properly. Unfortunately, our documentation is
silent about this setting. I will post a patch later.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2017-06-26 5:46 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-196157-27@https.bugzilla.kernel.org/>
2017-06-22 19:37 ` [Bug 196157] New: 100+ times slower disk writes on 4.x+/i386/16+RAM, compared to 3.x Andrew Morton
2017-06-22 20:58 ` Alkis Georgopoulos
2017-06-23 7:13 ` Michal Hocko
2017-06-23 7:44 ` Alkis Georgopoulos
2017-06-23 11:38 ` Michal Hocko
2017-06-26 5:28 ` Alkis Georgopoulos
2017-06-26 5:46 ` Michal Hocko [this message]
2017-06-26 7:02 ` Alkis Georgopoulos
2017-06-26 9:12 ` Michal Hocko
2017-06-29 6:14 ` Alkis Georgopoulos
2017-06-29 7:16 ` Michal Hocko
2017-06-29 8:02 ` Alkis Georgopoulos
2018-04-19 20:36 ` Andrew Morton
[not found] <234273956.1792577.1524210929280.ref@mail.yahoo.com>
2018-04-20 7:55 ` Thierry
[not found] <328204943.8183321.1534496501208.ref@mail.yahoo.com>
2018-08-17 9:01 ` Thierry
2018-08-17 9:29 ` Michal Hocko
[not found] <1978465524.8206495.1534505385491.ref@mail.yahoo.com>
2018-08-17 11:29 ` Thierry
2018-08-17 14:46 ` Michal Hocko
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