From: Johannes Weiner <hannes@cmpxchg.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: linux-mm@kvack.org, Joonsoo Kim <iamjoonsoo.kim@lge.com>,
David Rientjes <rientjes@google.com>,
Mel Gorman <mgorman@techsingularity.net>,
linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH v2 02/10] mm, compaction: remove redundant watermark check in compact_finished()
Date: Tue, 14 Feb 2017 11:34:53 -0500 [thread overview]
Message-ID: <20170214163453.GC2450@cmpxchg.org> (raw)
In-Reply-To: <20170210172343.30283-3-vbabka@suse.cz>
On Fri, Feb 10, 2017 at 06:23:35PM +0100, Vlastimil Babka wrote:
> When detecting whether compaction has succeeded in forming a high-order page,
> __compact_finished() employs a watermark check, followed by an own search for
> a suitable page in the freelists. This is not ideal for two reasons:
>
> - The watermark check also searches high-order freelists, but has a less strict
> criteria wrt fallback. It's therefore redundant and waste of cycles. This was
> different in the past when high-order watermark check attempted to apply
> reserves to high-order pages.
>
> - The watermark check might actually fail due to lack of order-0 pages.
> Compaction can't help with that, so there's no point in continuing because of
> that. It's possible that high-order page still exists and it terminates.
>
> This patch therefore removes the watermark check. This should save some cycles
> and terminate compaction sooner in some cases.
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes@cmpxchg.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: linux-mm@kvack.org, Joonsoo Kim <iamjoonsoo.kim@lge.com>,
David Rientjes <rientjes@google.com>,
Mel Gorman <mgorman@techsingularity.net>,
linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH v2 02/10] mm, compaction: remove redundant watermark check in compact_finished()
Date: Tue, 14 Feb 2017 11:34:53 -0500 [thread overview]
Message-ID: <20170214163453.GC2450@cmpxchg.org> (raw)
In-Reply-To: <20170210172343.30283-3-vbabka@suse.cz>
On Fri, Feb 10, 2017 at 06:23:35PM +0100, Vlastimil Babka wrote:
> When detecting whether compaction has succeeded in forming a high-order page,
> __compact_finished() employs a watermark check, followed by an own search for
> a suitable page in the freelists. This is not ideal for two reasons:
>
> - The watermark check also searches high-order freelists, but has a less strict
> criteria wrt fallback. It's therefore redundant and waste of cycles. This was
> different in the past when high-order watermark check attempted to apply
> reserves to high-order pages.
>
> - The watermark check might actually fail due to lack of order-0 pages.
> Compaction can't help with that, so there's no point in continuing because of
> that. It's possible that high-order page still exists and it terminates.
>
> This patch therefore removes the watermark check. This should save some cycles
> and terminate compaction sooner in some cases.
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
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next prev parent reply other threads:[~2017-02-14 16:35 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-10 17:23 [PATCH v2 00/10] try to reduce fragmenting fallbacks Vlastimil Babka
2017-02-10 17:23 ` Vlastimil Babka
2017-02-10 17:23 ` [PATCH v2 01/10] mm, compaction: reorder fields in struct compact_control Vlastimil Babka
2017-02-10 17:23 ` Vlastimil Babka
2017-02-13 10:49 ` Mel Gorman
2017-02-13 10:49 ` Mel Gorman
2017-02-14 16:33 ` Johannes Weiner
2017-02-14 16:33 ` Johannes Weiner
2017-02-10 17:23 ` [PATCH v2 02/10] mm, compaction: remove redundant watermark check in compact_finished() Vlastimil Babka
2017-02-10 17:23 ` Vlastimil Babka
2017-02-13 10:49 ` Mel Gorman
2017-02-13 10:49 ` Mel Gorman
2017-02-14 16:34 ` Johannes Weiner [this message]
2017-02-14 16:34 ` Johannes Weiner
2017-02-10 17:23 ` [PATCH v2 03/10] mm, page_alloc: split smallest stolen page in fallback Vlastimil Babka
2017-02-10 17:23 ` Vlastimil Babka
2017-02-13 10:51 ` Mel Gorman
2017-02-13 10:51 ` Mel Gorman
2017-02-13 10:54 ` Vlastimil Babka
2017-02-13 10:54 ` Vlastimil Babka
2017-02-14 16:59 ` Johannes Weiner
2017-02-14 16:59 ` Johannes Weiner
2017-02-10 17:23 ` [PATCH v2 04/10] mm, page_alloc: count movable pages when stealing from pageblock Vlastimil Babka
2017-02-10 17:23 ` Vlastimil Babka
2017-02-13 10:53 ` Mel Gorman
2017-02-13 10:53 ` Mel Gorman
2017-02-14 10:07 ` Xishi Qiu
2017-02-14 10:07 ` Xishi Qiu
2017-02-15 10:47 ` Vlastimil Babka
2017-02-15 10:47 ` Vlastimil Babka
2017-02-15 11:56 ` Xishi Qiu
2017-02-15 11:56 ` Xishi Qiu
2017-02-17 16:21 ` Vlastimil Babka
2017-02-17 16:21 ` Vlastimil Babka
2017-02-14 18:10 ` Johannes Weiner
2017-02-14 18:10 ` Johannes Weiner
2017-02-17 16:09 ` Vlastimil Babka
2017-02-17 16:09 ` Vlastimil Babka
2017-02-10 17:23 ` [PATCH v2 05/10] mm, compaction: change migrate_async_suitable() to suitable_migration_source() Vlastimil Babka
2017-02-10 17:23 ` Vlastimil Babka
2017-02-13 10:53 ` Mel Gorman
2017-02-13 10:53 ` Mel Gorman
2017-02-14 18:12 ` Johannes Weiner
2017-02-14 18:12 ` Johannes Weiner
2017-02-10 17:23 ` [PATCH v2 06/10] mm, compaction: add migratetype to compact_control Vlastimil Babka
2017-02-10 17:23 ` Vlastimil Babka
2017-02-13 10:53 ` Mel Gorman
2017-02-13 10:53 ` Mel Gorman
2017-02-14 18:15 ` Johannes Weiner
2017-02-14 18:15 ` Johannes Weiner
2017-02-10 17:23 ` [PATCH v2 07/10] mm, compaction: restrict async compaction to pageblocks of same migratetype Vlastimil Babka
2017-02-10 17:23 ` Vlastimil Babka
2017-02-13 10:56 ` Mel Gorman
2017-02-13 10:56 ` Mel Gorman
2017-02-14 20:10 ` Johannes Weiner
2017-02-14 20:10 ` Johannes Weiner
2017-02-17 16:32 ` Vlastimil Babka
2017-02-17 16:32 ` Vlastimil Babka
2017-02-17 17:39 ` Johannes Weiner
2017-02-17 17:39 ` Johannes Weiner
2017-02-10 17:23 ` [PATCH v2 08/10] mm, compaction: finish whole pageblock to reduce fragmentation Vlastimil Babka
2017-02-10 17:23 ` Vlastimil Babka
2017-02-13 10:57 ` Mel Gorman
2017-02-13 10:57 ` Mel Gorman
2017-02-16 11:44 ` Johannes Weiner
2017-02-16 11:44 ` Johannes Weiner
2017-02-10 17:23 ` [RFC v2 09/10] mm, page_alloc: disallow migratetype fallback in fastpath Vlastimil Babka
2017-02-10 17:23 ` Vlastimil Babka
2017-02-10 17:23 ` [RFC v2 10/10] mm, page_alloc: introduce MIGRATE_MIXED migratetype Vlastimil Babka
2017-02-10 17:23 ` Vlastimil Babka
2017-03-08 2:16 ` Yisheng Xie
2017-03-08 2:16 ` Yisheng Xie
2017-03-08 7:07 ` Vlastimil Babka
2017-03-08 7:07 ` Vlastimil Babka
2017-03-13 2:16 ` Yisheng Xie
2017-03-13 2:16 ` Yisheng Xie
2017-02-13 11:07 ` [PATCH v2 00/10] try to reduce fragmenting fallbacks Mel Gorman
2017-02-13 11:07 ` Mel Gorman
2017-02-15 14:29 ` Vlastimil Babka
2017-02-15 14:29 ` Vlastimil Babka
2017-02-15 16:11 ` Vlastimil Babka
2017-02-15 16:11 ` Vlastimil Babka
2017-02-15 20:11 ` Vlastimil Babka
2017-02-15 20:11 ` Vlastimil Babka
2017-02-16 15:12 ` Vlastimil Babka
2017-02-16 15:12 ` Vlastimil Babka
2017-02-17 15:24 ` Vlastimil Babka
2017-02-17 15:24 ` Vlastimil Babka
2017-02-20 12:30 ` Vlastimil Babka
2017-02-20 12:30 ` Vlastimil Babka
2017-02-23 16:01 ` Mel Gorman
2017-02-23 16:01 ` Mel Gorman
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