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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>

  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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