From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Hillf Danton <hdanton@sina.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Michal Hocko <mhocko@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>
Subject: Re: [PATCH 4/6] mm/page_alloc: Scale the number of pages that are batch freed
Date: Fri, 28 May 2021 13:19:45 +0200 [thread overview]
Message-ID: <c7e5a4e7-43df-0f49-d297-1b4621221ca1@suse.cz> (raw)
In-Reply-To: <20210525080119.5455-5-mgorman@techsingularity.net>
On 5/25/21 10:01 AM, Mel Gorman wrote:
> When a task is freeing a large number of order-0 pages, it may acquire
> the zone->lock multiple times freeing pages in batches. This may
> unnecessarily contend on the zone lock when freeing very large number
> of pages. This patch adapts the size of the batch based on the recent
> pattern to scale the batch size for subsequent frees.
>
> As the machines I used were not large enough to test this are not large
> enough to illustrate a problem, a debugging patch shows patterns like
> the following (slightly editted for clarity)
>
> Baseline vanilla kernel
> time-unmap-14426 [...] free_pcppages_bulk: free 63 count 378 high 378
> time-unmap-14426 [...] free_pcppages_bulk: free 63 count 378 high 378
> time-unmap-14426 [...] free_pcppages_bulk: free 63 count 378 high 378
> time-unmap-14426 [...] free_pcppages_bulk: free 63 count 378 high 378
> time-unmap-14426 [...] free_pcppages_bulk: free 63 count 378 high 378
>
> With patches
> time-unmap-7724 [...] free_pcppages_bulk: free 126 count 814 high 814
> time-unmap-7724 [...] free_pcppages_bulk: free 252 count 814 high 814
> time-unmap-7724 [...] free_pcppages_bulk: free 504 count 814 high 814
> time-unmap-7724 [...] free_pcppages_bulk: free 751 count 814 high 814
> time-unmap-7724 [...] free_pcppages_bulk: free 751 count 814 high 814
>
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
> Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
next prev parent reply other threads:[~2021-05-28 11:20 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-25 8:01 [PATCH 0/6 v2] Calculate pcp->high based on zone sizes and active CPUs Mel Gorman
2021-05-25 8:01 ` [PATCH 1/6] mm/page_alloc: Delete vm.percpu_pagelist_fraction Mel Gorman
2021-05-26 17:41 ` Vlastimil Babka
2021-05-25 8:01 ` [PATCH 2/6] mm/page_alloc: Disassociate the pcp->high from pcp->batch Mel Gorman
2021-05-26 18:14 ` Vlastimil Babka
2021-05-27 10:52 ` Mel Gorman
2021-05-28 10:27 ` Vlastimil Babka
2021-05-25 8:01 ` [PATCH 3/6] mm/page_alloc: Adjust pcp->high after CPU hotplug events Mel Gorman
2021-05-28 11:08 ` Vlastimil Babka
2021-05-25 8:01 ` [PATCH 4/6] mm/page_alloc: Scale the number of pages that are batch freed Mel Gorman
2021-05-28 11:19 ` Vlastimil Babka [this message]
2021-05-25 8:01 ` [PATCH 5/6] mm/page_alloc: Limit the number of pages on PCP lists when reclaim is active Mel Gorman
2021-05-28 11:43 ` Vlastimil Babka
2021-05-25 8:01 ` [PATCH 6/6] mm/page_alloc: Introduce vm.percpu_pagelist_high_fraction Mel Gorman
2021-05-28 11:59 ` Vlastimil Babka
2021-05-28 12:53 ` Mel Gorman
2021-05-28 14:38 ` Vlastimil Babka
2021-05-27 19:36 ` [PATCH 0/6 v2] Calculate pcp->high based on zone sizes and active CPUs Dave Hansen
2021-05-28 8:55 ` Mel Gorman
2021-05-28 9:03 ` David Hildenbrand
2021-05-28 9:08 ` David Hildenbrand
2021-05-28 9:49 ` Mel Gorman
2021-05-28 9:52 ` David Hildenbrand
2021-05-28 10:09 ` Mel Gorman
2021-05-28 10:21 ` David Hildenbrand
2021-05-28 12:12 ` Vlastimil Babka
2021-05-28 12:37 ` Mel Gorman
2021-05-28 14:39 ` Dave Hansen
2021-05-28 15:18 ` Mel Gorman
2021-05-28 16:17 ` Dave Hansen
2021-05-31 12:00 ` Feng Tang
-- strict thread matches above, loose matches on Subject: below --
2021-05-21 10:28 [RFC PATCH 0/6] " Mel Gorman
2021-05-21 10:28 ` [PATCH 4/6] mm/page_alloc: Scale the number of pages that are batch freed Mel Gorman
2021-05-21 22:36 ` Dave Hansen
2021-05-24 9:12 ` Mel Gorman
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