From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Rik van Riel <riel@redhat.com>,
David Rientjes <rientjes@google.com>,
Mel Gorman <mgorman@techsingularity.net>,
Johannes Weiner <hannes@cmpxchg.org>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [RFC 12/13] mm, compaction: more reliably increase direct compaction priority
Date: Mon, 16 May 2016 11:52:36 +0200 [thread overview]
Message-ID: <20160516095236.GF23146@dhcp22.suse.cz> (raw)
In-Reply-To: <5739929C.5000500@suse.cz>
On Mon 16-05-16 11:27:56, Vlastimil Babka wrote:
> On 05/16/2016 10:14 AM, Michal Hocko wrote:
> > On Mon 16-05-16 09:31:44, Vlastimil Babka wrote:
[...]
> > > Also my understanding of the initial compaction priorities is to lower the
> > > latency if fragmentation is just light and there's enough memory. Once we
> > > start struggling, I don't see much point in not switching to the full
> > > compaction priority quickly.
> >
> > That is true but why to compact when there are high order pages and they
> > are just hidden by the watermark check.
>
> Compaction should skip such zone regardless of priority.
The point I've tried to raise is that we shouldn't conflate the purpose
of the two. The reclaim is here primarily to get us over the watermarks
while compaction is here to form high order pages. If we get both
together the distinction is blured which, I believe, will lead to more
complicated code in the end. I might be wrong here of course but let's
try to have compaction as much wmark check free as possible.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2016-05-16 9:52 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-10 7:35 [RFC 00/13] make direct compaction more deterministic Vlastimil Babka
2016-05-10 7:35 ` [RFC 01/13] mm, compaction: don't isolate PageWriteback pages in MIGRATE_SYNC_LIGHT mode Vlastimil Babka
2016-05-11 12:40 ` Michal Hocko
2016-05-10 7:35 ` [RFC 02/13] mm, page_alloc: set alloc_flags only once in slowpath Vlastimil Babka
2016-05-10 11:28 ` Tetsuo Handa
2016-05-10 12:30 ` Vlastimil Babka
2016-05-12 12:41 ` Michal Hocko
2016-05-31 6:20 ` Joonsoo Kim
2016-05-31 7:59 ` Vlastimil Babka
2016-06-02 1:50 ` Joonsoo Kim
2016-05-10 7:35 ` [RFC 03/13] mm, page_alloc: don't retry initial attempt " Vlastimil Babka
2016-05-12 12:48 ` Michal Hocko
2016-05-31 6:25 ` Joonsoo Kim
2016-05-31 12:03 ` Vlastimil Babka
2016-05-10 7:35 ` [RFC 04/13] mm, page_alloc: restructure direct compaction handling " Vlastimil Babka
2016-05-12 13:29 ` Michal Hocko
2016-05-13 8:10 ` Vlastimil Babka
2016-05-13 8:31 ` Michal Hocko
2016-05-10 7:35 ` [RFC 05/13] mm, page_alloc: make THP-specific decisions more generic Vlastimil Babka
2016-05-12 13:43 ` Michal Hocko
2016-05-10 7:35 ` [RFC 06/13] mm, thp: remove __GFP_NORETRY from khugepaged and madvised allocations Vlastimil Babka
2016-05-12 16:20 ` Michal Hocko
2016-05-13 8:23 ` Vlastimil Babka
2016-05-13 12:05 ` Michal Hocko
2016-05-18 11:59 ` Vlastimil Babka
2016-05-18 15:24 ` Michal Hocko
2016-05-20 13:57 ` Vlastimil Babka
2016-05-23 8:39 ` Michal Hocko
2016-05-10 7:35 ` [RFC 07/13] mm, compaction: introduce direct compaction priority Vlastimil Babka
2016-05-13 12:37 ` Michal Hocko
2016-05-10 7:35 ` [RFC 08/13] mm, compaction: simplify contended compaction handling Vlastimil Babka
2016-05-13 13:09 ` Michal Hocko
2016-05-16 7:10 ` Vlastimil Babka
2016-05-10 7:35 ` [RFC 09/13] mm, compaction: make whole_zone flag ignore cached scanner positions Vlastimil Babka
2016-05-13 13:23 ` Michal Hocko
2016-05-10 7:36 ` [RFC 10/13] mm, compaction: cleanup unused functions Vlastimil Babka
2016-05-10 7:36 ` [RFC 11/13] mm, compaction: add the ultimate direct compaction priority Vlastimil Babka
2016-05-13 13:38 ` Michal Hocko
2016-05-16 7:17 ` Vlastimil Babka
2016-05-16 8:11 ` Michal Hocko
2016-05-18 12:46 ` Vlastimil Babka
2016-05-10 7:36 ` [RFC 12/13] mm, compaction: more reliably increase " Vlastimil Babka
2016-05-10 12:55 ` Vlastimil Babka
2016-05-13 14:15 ` Michal Hocko
2016-05-16 7:31 ` Vlastimil Babka
2016-05-16 8:14 ` Michal Hocko
2016-05-16 9:27 ` Vlastimil Babka
2016-05-16 9:52 ` Michal Hocko [this message]
2016-05-31 6:37 ` Joonsoo Kim
2016-05-31 12:07 ` Vlastimil Babka
2016-05-31 12:29 ` Vlastimil Babka
2016-06-02 2:50 ` Joonsoo Kim
2016-05-10 7:36 ` [RFC 13/13] mm, compaction: fix and improve watermark handling Vlastimil Babka
2016-05-16 9:25 ` Michal Hocko
2016-05-16 9:50 ` Vlastimil Babka
2016-05-16 12:30 ` Michal Hocko
2016-05-18 13:50 ` Mel Gorman
2016-05-18 14:27 ` Michal Hocko
2016-05-18 14:40 ` Mel Gorman
2016-05-17 20:01 ` [RFC 00/13] make direct compaction more deterministic Michal Hocko
2016-05-18 7:19 ` Vlastimil Babka
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