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From: Dave Hansen <dave.hansen@intel.com>
To: Mel Gorman <mgorman@techsingularity.net>, Linux-MM <linux-mm@kvack.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
	Matthew Wilcox <willy@infradead.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Michal Hocko <mhocko@kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 6/6] mm/page_alloc: Introduce vm.percpu_pagelist_high_fraction
Date: Fri, 21 May 2021 15:57:20 -0700	[thread overview]
Message-ID: <ab7cbd43-7952-ca23-0a5c-379dfcfb14ba@intel.com> (raw)
In-Reply-To: <20210521102826.28552-7-mgorman@techsingularity.net>

On 5/21/21 3:28 AM, Mel Gorman wrote:
> This introduces a new sysctl vm.percpu_pagelist_high_fraction. It is
> similar to the old vm.percpu_pagelist_fraction except it only adjusts
> pcp->high to potentially reduce zone->lock contention while preserving
> allocation latency when PCP lists have to be refilled.

Look at me...  Five patches later and I already forgot what the old one
did and why it stinks.  I wonder if you might do a wee bit of compare
and contrast.  Something like:

	The old vm.percpu_pagelist_fraction increased both the batch and
	high limits for the per-cpu page allocator.  Its worst feature
	was that it led to absurdly large batch sizes that incurred
	nasty worst-case allocation latency.

	This new sysctl in comparison...

Anyway, the approach looks sound to me.  The batch size isn't important
now, especially given the auto-scaling in patch 4.

Acked-by: Dave Hansen <dave.hansen@linux.intel.com>

  reply	other threads:[~2021-05-21 22:57 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-21 10:28 [RFC PATCH 0/6] Calculate pcp->high based on zone sizes and active CPUs Mel Gorman
2021-05-21 10:28 ` [PATCH 1/6] mm/page_alloc: Delete vm.percpu_pagelist_fraction Mel Gorman
2021-05-21 21:04   ` Dave Hansen
2021-05-21 10:28 ` [PATCH 2/6] mm/page_alloc: Disassociate the pcp->high from pcp->batch Mel Gorman
2021-05-21 21:52   ` Dave Hansen
2021-05-24  8:32     ` Mel Gorman
2021-05-21 10:28 ` [PATCH 3/6] mm/page_alloc: Adjust pcp->high after CPU hotplug events Mel Gorman
2021-05-21 22:13   ` Dave Hansen
2021-05-24  9:07     ` Mel Gorman
2021-05-24 15:52       ` Dave Hansen
2021-05-24 16:01         ` 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
2021-05-21 10:28 ` [PATCH 5/6] mm/page_alloc: Limit the number of pages on PCP lists when reclaim is active Mel Gorman
2021-05-21 22:44   ` Dave Hansen
2021-05-24  9:22     ` Mel Gorman
2021-05-21 10:28 ` [PATCH 6/6] mm/page_alloc: Introduce vm.percpu_pagelist_high_fraction Mel Gorman
2021-05-21 22:57   ` Dave Hansen [this message]
2021-05-24  9:25     ` Mel Gorman
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 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

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