From: Mel Gorman <mgorman@techsingularity.net>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Linux-MM <linux-mm@kvack.org>,
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 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: <e9061a5c-bbef-e818-94f7-95e21a73a948@intel.com>
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 16:01 UTC|newest]
Thread overview: 23+ 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
2021-05-22 2:19 ` Hillf Danton
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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