From: Mel Gorman <mgorman@techsingularity.net>
To: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: akpm@linux-foundation.org, vbabka@suse.cz, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] mm: compaction: update the cc->nr_migratepages when allocating or freeing the freepages
Date: Thu, 1 Feb 2024 10:30:09 +0000 [thread overview]
Message-ID: <20240201103009.jycolrj7t3axtlgd@techsingularity.net> (raw)
In-Reply-To: <0773058df022fa701b78f9a6dfe3c501a1a77351.1705928395.git.baolin.wang@linux.alibaba.com>
On Mon, Jan 22, 2024 at 09:01:54PM +0800, Baolin Wang wrote:
> Currently we will use 'cc->nr_freepages >= cc->nr_migratepages' comparison
> to ensure that enough freepages are isolated in isolate_freepages(), however
> it just decreases the cc->nr_freepages without updating cc->nr_migratepages
> in compaction_alloc(), which will waste more CPU cycles and cause too many
> freepages to be isolated.
>
> So we should also update the cc->nr_migratepages when allocating or freeing
> the freepages to avoid isolating excess freepages. And I can see fewer free
> pages are scanned and isolated when running thpcompact on my Arm64 server:
> k6.7 k6.7_patched
> Ops Compaction pages isolated 120692036.00 118160797.00
> Ops Compaction migrate scanned 131210329.00 154093268.00
> Ops Compaction free scanned 1090587971.00 1080632536.00
> Ops Compact scan efficiency 12.03 14.26
>
> Moreover, I did not see an obvious latency improvements, this is likely because
> isolating freepages is not the bottleneck in the thpcompact test case.
> k6.7 k6.7_patched
> Amean fault-both-1 1089.76 ( 0.00%) 1080.16 * 0.88%*
> Amean fault-both-3 1616.48 ( 0.00%) 1636.65 * -1.25%*
> Amean fault-both-5 2266.66 ( 0.00%) 2219.20 * 2.09%*
> Amean fault-both-7 2909.84 ( 0.00%) 2801.90 * 3.71%*
> Amean fault-both-12 4861.26 ( 0.00%) 4733.25 * 2.63%*
> Amean fault-both-18 7351.11 ( 0.00%) 6950.51 * 5.45%*
> Amean fault-both-24 9059.30 ( 0.00%) 9159.99 * -1.11%*
> Amean fault-both-30 10685.68 ( 0.00%) 11399.02 * -6.68%*
>
> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2024-02-01 10:30 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-22 13:01 [PATCH 1/2] mm: compaction: limit the suitable target page order to be less than cc->order Baolin Wang
2024-01-22 13:01 ` [PATCH 2/2] mm: compaction: update the cc->nr_migratepages when allocating or freeing the freepages Baolin Wang
2024-02-01 10:30 ` Mel Gorman [this message]
2024-02-12 10:32 ` Vlastimil Babka
2024-02-19 2:34 ` Baolin Wang
2024-02-01 10:29 ` [PATCH 1/2] mm: compaction: limit the suitable target page order to be less than cc->order Mel Gorman
2024-02-12 9:13 ` Vlastimil Babka
2024-02-12 15:00 ` Zi Yan
2024-02-19 2:55 ` Baolin Wang
2024-02-21 22:15 ` Andrew Morton
2024-02-21 22:22 ` Vlastimil Babka
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