From: Mel Gorman <email@example.com> To: Dave Hansen <firstname.lastname@example.org> Cc: Linux-MM <email@example.com>, Dave Hansen <firstname.lastname@example.org>, Matthew Wilcox <email@example.com>, Vlastimil Babka <firstname.lastname@example.org>, Michal Hocko <email@example.com>, Nicholas Piggin <firstname.lastname@example.org>, LKML <email@example.com> Subject: Re: [PATCH 3/6] mm/page_alloc: Adjust pcp->high after CPU hotplug events Date: Mon, 24 May 2021 17:01:01 +0100 [thread overview] Message-ID: <20210524160101.GG30378@techsingularity.net> (raw) In-Reply-To: <firstname.lastname@example.org> On Mon, May 24, 2021 at 08:52:02AM -0700, Dave Hansen wrote: > > To address your point requires much deeper surgery. > ... > > There is value to doing something like this but it's beyond what this > > series is trying to do and doing the work without introducing regressions > > would be very difficult. > > Agreed, such a solution is outside of the scope of what this set is > trying to do. > > It would be nice to touch on this counter-intuitive property in the > changelog, and *maybe* add a WARN_ON_ONCE() if we hit an edge case. > Maybe WARN_ON_ONCE() if pcp->high gets below pcp->batch*SOMETHING. > I think it's reasonable to ensure pcp->batch is never above pcp->high so I have this in zone_highsize now + /* + * Ensure high is at least batch*4. The multiple is based on the + * historical relationship between high and batch. + */ + high = max(high, batch << 2); Performance tests are running and I'll post a v2 assuming they pass. -- Mel Gorman SUSE Labs
next prev parent reply other threads:[~2021-05-24 16:09 UTC|newest] Thread overview: 22+ 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 [this message] 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 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 3/6] mm/page_alloc: Adjust pcp->high after CPU hotplug events Mel Gorman 2021-05-28 11:08 ` Vlastimil Babka
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