From: Michal Hocko <mhocko@kernel.org>
To: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/thp: don't count ZONE_MOVABLE as the target for freepage reserving
Date: Thu, 5 Apr 2018 10:27:08 +0200 [thread overview]
Message-ID: <20180405082708.GA6312@dhcp22.suse.cz> (raw)
In-Reply-To: <20180405080539.GA631@js1304-desktop>
On Thu 05-04-18 17:05:39, Joonsoo Kim wrote:
> On Thu, Apr 05, 2018 at 09:57:53AM +0200, Michal Hocko wrote:
> > On Thu 05-04-18 16:27:16, Joonsoo Kim wrote:
> > > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > >
> > > ZONE_MOVABLE only has movable pages so we don't need to keep enough
> > > freepages to avoid or deal with fragmentation. So, don't count it.
> > >
> > > This changes min_free_kbytes and thus min_watermark greatly
> > > if ZONE_MOVABLE is used. It will make the user uses more memory.
> >
> > OK, but why does it matter. Has anybody seen this as an issue?
>
> There was a regression report for CMA patchset and I think that it is
> related to this problem. CMA patchset makes the system uses one more
> zone (ZONE_MOVABLE) and then increase min_free_kbytes. It reduces
> usable memory and it could cause regression.
>
> http://lkml.kernel.org/r/20180102063528.GG30397@yexl-desktop
Then this should be a part of the changelog along with some reproducible
results, please.
--
Michal Hocko
SUSE Labs
prev parent reply other threads:[~2018-04-05 8:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-05 7:27 [PATCH] mm/thp: don't count ZONE_MOVABLE as the target for freepage reserving js1304
2018-04-05 7:57 ` Michal Hocko
2018-04-05 8:05 ` Joonsoo Kim
2018-04-05 8:10 ` Joonsoo Kim
2018-04-05 8:27 ` Michal Hocko [this message]
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