From: Dave Hansen <firstname.lastname@example.org> To: Mel Gorman <email@example.com>, Linux-MM <firstname.lastname@example.org> Cc: Dave Hansen <email@example.com>, Matthew Wilcox <firstname.lastname@example.org>, Vlastimil Babka <email@example.com>, Michal Hocko <firstname.lastname@example.org>, Nicholas Piggin <email@example.com>, LKML <firstname.lastname@example.org> Subject: Re: [PATCH 1/6] mm/page_alloc: Delete vm.percpu_pagelist_fraction Date: Fri, 21 May 2021 14:04:25 -0700 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <firstname.lastname@example.org> On 5/21/21 3:28 AM, Mel Gorman wrote: > The vm.percpu_pagelist_fraction is used to increase the batch and high > limits for the per-cpu page allocator (PCP). The intent behind the sysctl > is to reduce zone lock acquisition when allocating/freeing pages but it has > a problem. While it can decrease contention, it can also increase latency > on the allocation side due to unreasonably large batch sizes. This leads > to games where an administrator adjusts percpu_pagelist_fraction on the > fly to work around contention and allocation latency problems. > > This series aims to alleviate the problems with zone lock contention while > avoiding the allocation-side latency problems. For the purposes of review, > it's easier to remove this sysctl now and reintroduce a similar sysctl > later in the series that deals only with pcp->high. > > Signed-off-by: Mel Gorman <email@example.com> I despise working with percpu_pagelist_fraction. I usually just end up poking random numbers into it and then checking what the fallout looks like in /proc/zoneinfo is. Good riddance. Acked-by: Dave Hansen <firstname.lastname@example.org>
next prev parent reply other threads:[~2021-05-21 21:04 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 [this message] 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 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 1/6] mm/page_alloc: Delete vm.percpu_pagelist_fraction Mel Gorman 2021-05-26 17:41 ` Vlastimil Babka
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --subject='Re: [PATCH 1/6] mm/page_alloc: Delete vm.percpu_pagelist_fraction' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).