From: David Hildenbrand <email@example.com> To: Mel Gorman <firstname.lastname@example.org>, Dave Hansen <email@example.com> Cc: Andrew Morton <firstname.lastname@example.org>, Hillf Danton <email@example.com>, Dave Hansen <firstname.lastname@example.org>, Vlastimil Babka <email@example.com>, Michal Hocko <firstname.lastname@example.org>, LKML <email@example.com>, Linux-MM <firstname.lastname@example.org>, "Tang, Feng" <email@example.com> Subject: Re: [PATCH 0/6 v2] Calculate pcp->high based on zone sizes and active CPUs Date: Fri, 28 May 2021 11:08:01 +0200 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) In-Reply-To: <email@example.com> On 28.05.21 11:03, David Hildenbrand wrote: > On 28.05.21 10:55, Mel Gorman wrote: >> On Thu, May 27, 2021 at 12:36:21PM -0700, Dave Hansen wrote: >>> Hi Mel, >>> >>> Feng Tang tossed these on a "Cascade Lake" system with 96 threads and >>> ~512G of persistent memory and 128G of DRAM. The PMEM is in "volatile >>> use" mode and being managed via the buddy just like the normal RAM. >>> >>> The PMEM zones are big ones: >>> >>> present 65011712 = 248 G >>> high 134595 = 525 M >>> >>> The PMEM nodes, of course, don't have any CPUs in them. >>> >>> With your series, the pcp->high value per-cpu is 69584 pages or about >>> 270MB per CPU. Scaled up by the 96 CPU threads, that's ~26GB of >>> worst-case memory in the pcps per zone, or roughly 10% of the size of >>> the zone. > > When I read about having such big amounts of free memory theoretically > stuck in PCP lists, I guess we really want to start draining the PCP in > alloc_contig_range(), just as we do with memory hotunplug when offlining. > Correction: we already drain the pcp, we just don't temporarily disable it, so a race as described in offline_pages() could apply: "Disable pcplists so that page isolation cannot race with freeing in a way that pages from isolated pageblock are left on pcplists." Guess we'd then want to move the draining before start_isolate_page_range() in alloc_contig_range(). -- Thanks, David / dhildenb
next prev parent reply other threads:[~2021-05-28 9:08 UTC|newest] Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-25 8:01 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 2021-05-25 8:01 ` [PATCH 2/6] mm/page_alloc: Disassociate the pcp->high from pcp->batch Mel Gorman 2021-05-26 18:14 ` Vlastimil Babka 2021-05-27 10:52 ` Mel Gorman 2021-05-28 10:27 ` Vlastimil Babka 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 2021-05-25 8:01 ` [PATCH 4/6] mm/page_alloc: Scale the number of pages that are batch freed Mel Gorman 2021-05-28 11:19 ` Vlastimil Babka 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 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 2021-05-27 19:36 ` [PATCH 0/6 v2] Calculate pcp->high based on zone sizes and active CPUs Dave Hansen 2021-05-28 8:55 ` Mel Gorman 2021-05-28 9:03 ` David Hildenbrand 2021-05-28 9:08 ` David Hildenbrand [this message] 2021-05-28 9:49 ` Mel Gorman 2021-05-28 9:52 ` David Hildenbrand 2021-05-28 10:09 ` Mel Gorman 2021-05-28 10:21 ` David Hildenbrand 2021-05-28 12:12 ` Vlastimil Babka 2021-05-28 12:37 ` Mel Gorman 2021-05-28 14:39 ` Dave Hansen 2021-05-28 15:18 ` Mel Gorman 2021-05-28 16:17 ` Dave Hansen 2021-05-31 12:00 ` Feng Tang
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