From: Mel Gorman <mgorman@techsingularity.net>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Arjan Van De Ven <arjan@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
David Hildenbrand <david@redhat.com>,
Johannes Weiner <jweiner@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Michal Hocko <mhocko@suse.com>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
Matthew Wilcox <willy@infradead.org>,
Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH 09/10] mm, pcp: avoid to reduce PCP high unnecessarily
Date: Thu, 12 Oct 2023 13:49:58 +0100 [thread overview]
Message-ID: <20231012124958.dj5ug5hih3joa542@techsingularity.net> (raw)
In-Reply-To: <87lec8ffij.fsf@yhuang6-desk2.ccr.corp.intel.com>
On Thu, Oct 12, 2023 at 03:48:04PM +0800, Huang, Ying wrote:
> "
> On a 2-socket Intel server with 224 logical CPU, we run 8 kbuild
> instances in parallel (each with `make -j 28`) in 8 cgroup. This
> simulates the kbuild server that is used by 0-Day kbuild service.
> With the patch, The number of pages allocated from zone (instead of
> from PCP) decreases 21.4%.
> "
>
> I also showed the performance number for each step of optimization as
> follows (copied from the above patchset V2 link).
>
> "
> build time lock contend% free_high alloc_zone
> ---------- ---------- --------- ----------
> base 100.0 13.5 100.0 100.0
> patch1 99.2 10.6 19.2 95.6
> patch3 99.2 11.7 7.1 95.6
> patch5 98.4 10.0 8.2 97.1
> patch7 94.9 0.7 3.0 19.0
> patch9 94.9 0.6 2.7 15.0 <-- this patch
> patch10 94.9 0.9 8.8 18.6
> "
>
> Although I think the patch is helpful via avoiding the unnecessary
> pcp->high decaying, thus reducing the zone lock contention. There's no
> visible benchmark score change for the patch.
>
Thanks!
Given that it's another PCP field with an update in a relatively hot
path, I would suggest dropping this patch entirely if it does not affect
performance. It has the risk of being a magical heuristic that we forget
later whether it's even worthwhile.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2023-10-12 12:50 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-20 6:18 [PATCH 00/10] mm: PCP high auto-tuning Huang Ying
2023-09-20 6:18 ` [PATCH 01/10] mm, pcp: avoid to drain PCP when process exit Huang Ying
2023-10-11 12:46 ` Mel Gorman
2023-10-11 17:16 ` Andrew Morton
2023-10-12 13:09 ` Mel Gorman
2023-10-12 13:35 ` Huang, Ying
2023-10-12 12:21 ` Huang, Ying
2023-09-20 6:18 ` [PATCH 02/10] cacheinfo: calculate per-CPU data cache size Huang Ying
2023-09-20 9:24 ` Sudeep Holla
2023-09-22 7:56 ` Huang, Ying
2023-10-11 12:20 ` Mel Gorman
2023-10-12 12:08 ` Huang, Ying
2023-10-12 12:52 ` Mel Gorman
2023-10-12 13:12 ` Huang, Ying
2023-10-12 15:22 ` Mel Gorman
2023-10-13 3:06 ` Huang, Ying
2023-10-16 15:43 ` Mel Gorman
2023-09-20 6:18 ` [PATCH 03/10] mm, pcp: reduce lock contention for draining high-order pages Huang Ying
2023-10-11 12:49 ` Mel Gorman
2023-10-12 12:11 ` Huang, Ying
2023-09-20 6:18 ` [PATCH 04/10] mm: restrict the pcp batch scale factor to avoid too long latency Huang Ying
2023-10-11 12:52 ` Mel Gorman
2023-10-12 12:15 ` Huang, Ying
2023-09-20 6:18 ` [PATCH 05/10] mm, page_alloc: scale the number of pages that are batch allocated Huang Ying
2023-10-11 12:54 ` Mel Gorman
2023-09-20 6:18 ` [PATCH 06/10] mm: add framework for PCP high auto-tuning Huang Ying
2023-09-20 6:18 ` [PATCH 07/10] mm: tune PCP high automatically Huang Ying
2023-09-20 6:18 ` [PATCH 08/10] mm, pcp: decrease PCP high if free pages < high watermark Huang Ying
2023-10-11 13:08 ` Mel Gorman
2023-10-12 12:19 ` Huang, Ying
2023-09-20 6:18 ` [PATCH 09/10] mm, pcp: avoid to reduce PCP high unnecessarily Huang Ying
2023-10-11 14:09 ` Mel Gorman
2023-10-12 7:48 ` Huang, Ying
2023-10-12 12:49 ` Mel Gorman [this message]
2023-10-12 13:19 ` Huang, Ying
2023-09-20 6:18 ` [PATCH 10/10] mm, pcp: reduce detecting time of consecutive high order page freeing Huang Ying
2023-09-20 16:41 ` [PATCH 00/10] mm: PCP high auto-tuning Andrew Morton
2023-09-21 13:32 ` Huang, Ying
2023-09-21 15:46 ` Andrew Morton
2023-09-22 0:33 ` Huang, Ying
2023-10-11 13:05 ` Mel Gorman
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