From: Vlastimil Babka <vbabka@suse.cz>
To: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@kernel.org>,
Mel Gorman <mgorman@techsingularity.net>,
David Rientjes <rientjes@google.com>,
Rik van Riel <riel@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 04/11] mm, compaction: don't recheck watermarks after COMPACT_SUCCESS
Date: Tue, 16 Aug 2016 08:11:21 +0200 [thread overview]
Message-ID: <7cd558df-d815-2e05-6a24-d1e1c87f184f@suse.cz> (raw)
In-Reply-To: <20160816061200.GD17448@js1304-P5Q-DELUXE>
On 08/16/2016 08:12 AM, Joonsoo Kim wrote:
> On Wed, Aug 10, 2016 at 11:12:19AM +0200, Vlastimil Babka wrote:
>> Joonsoo has reminded me that in a later patch changing watermark checks
>> throughout compaction I forgot to update checks in try_to_compact_pages() and
>> compactd_do_work(). Closer inspection however shows that they are redundant now
>> that compact_zone() reliably reports success with COMPACT_SUCCESS, as they just
>> repeat (a subset) of checks that have just passed. So instead of checking
>> watermarks again, just test the return value.
>
> In fact, it's not redundant. Even if try_to_compact_pages() returns
> !COMPACT_SUCCESS, watermark check could return true.
Right, I meant they are redundant in the SUCCESS case.
> __compact_finished() calls find_suitable_fallback() and it's slightly
> different with watermark check. Anyway, I don't think it is a big
> problem.
I agree. It might be even better for long-term fragmentation that we
e.g. try another zone instead of taking page from the "unsuitable
fallback". If that's not successful, and the allocation is important
enough there will later eventually be another watermark check permitting
the unsuitable fallback.
Thanks.
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next prev parent reply other threads:[~2016-08-16 6:11 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-10 9:12 [PATCH v6 00/11] make direct compaction more deterministic Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 01/11] mm, compaction: make whole_zone flag ignore cached scanner positions Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 02/11] mm, compaction: cleanup unused functions Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 03/11] mm, compaction: rename COMPACT_PARTIAL to COMPACT_SUCCESS Vlastimil Babka
2016-08-18 9:01 ` Michal Hocko
2016-08-10 9:12 ` [PATCH v6 04/11] mm, compaction: don't recheck watermarks after COMPACT_SUCCESS Vlastimil Babka
2016-08-16 6:12 ` Joonsoo Kim
2016-08-16 6:11 ` Vlastimil Babka [this message]
2016-08-18 11:59 ` Vlastimil Babka
2016-08-18 9:03 ` Michal Hocko
2016-08-10 9:12 ` [PATCH v6 05/11] mm, compaction: add the ultimate direct compaction priority Vlastimil Babka
2016-08-16 5:58 ` Joonsoo Kim
2016-08-18 12:23 ` Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 06/11] mm, compaction: more reliably increase " Vlastimil Babka
2016-08-16 6:07 ` Joonsoo Kim
2016-08-16 6:31 ` Vlastimil Babka
2016-08-18 9:10 ` Michal Hocko
2016-08-18 9:44 ` Vlastimil Babka
2016-08-18 9:48 ` Michal Hocko
2016-08-10 9:12 ` [PATCH v6 07/11] mm, compaction: use correct watermark when checking compaction success Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 08/11] mm, compaction: create compact_gap wrapper Vlastimil Babka
2016-08-16 6:15 ` Joonsoo Kim
2016-08-16 6:15 ` Vlastimil Babka
2016-08-16 6:41 ` Joonsoo Kim
2016-08-18 12:13 ` Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 09/11] mm, compaction: use proper alloc_flags in __compaction_suitable() Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 10/11] mm, compaction: require only min watermarks for non-costly orders Vlastimil Babka
2016-08-16 6:16 ` Joonsoo Kim
2016-08-16 6:36 ` Vlastimil Babka
2016-08-16 6:46 ` Joonsoo Kim
2016-08-18 12:20 ` Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 11/11] mm, vmscan: make compaction_ready() more accurate and readable Vlastimil Babka
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