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 5/6] mm/page_alloc: Limit the number of pages on PCP lists when reclaim is active
Date: Fri, 21 May 2021 15:44:49 -0700 [thread overview]
Message-ID: <3f0ebd90-1aca-1dfc-3b92-bdb991d0fb29@intel.com> (raw)
In-Reply-To: <20210521102826.28552-6-mgorman@techsingularity.net>
On 5/21/21 3:28 AM, Mel Gorman wrote:
> +static int nr_pcp_high(struct per_cpu_pages *pcp, struct zone *zone)
> +{
> + int high = READ_ONCE(pcp->high);
> +
> + if (unlikely(!high))
> + return 0;
> +
> + if (!test_bit(ZONE_RECLAIM_ACTIVE, &zone->flags))
> + return high;
> +
> + /*
> + * If reclaim is active, limit the number of pages that can be
> + * stored on pcp lists
> + */
> + return READ_ONCE(pcp->batch) << 2;
> +}
Should there be a sanity check on this? Let's say we had one of those
weirdo zones with tons of CPUs and a small low_wmark_pages(). Could we
have a case where:
pcp->high < pcp->batch<<2
and this effectively *raises* nr_pcp_high()?
It's not possible with the current pcp->high calculation, but does
anything prevent it now?
next prev parent reply other threads:[~2021-05-21 22:44 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
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 [this message]
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 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
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