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From: Shakeel Butt <shakeelb@google.com>
To: Rik van Riel <riel@surriel.com>
Cc: "Huang, Ying" <ying.huang@intel.com>, Yu Zhao <yuzhao@google.com>,
	Dave Chinner <david@fromorbit.com>, Jens Axboe <axboe@kernel.dk>,
	SeongJae Park <sj38.park@gmail.com>,
	Linux-MM <linux-mm@kvack.org>, Andi Kleen <ak@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Benjamin Manes <ben.manes@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Hillf Danton <hdanton@sina.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Matthew Wilcox <willy@infradead.org>,
	Mel Gorman <mgorman@suse.de>, Miaohe Lin <linmiaohe@huawei.com>,
	Michael Larabel <michael@michaellarabel.com>,
	Michal Hocko <mhocko@suse.com>,
	Michel Lespinasse <michel@lespinasse.org>,
	Roman Gushchin <guro@fb.com>, Rong Chen <rong.a.chen@intel.com>,
	SeongJae Park <sjpark@amazon.de>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Vlastimil Babka <vbabka@suse.cz>, Yang Shi <shy828301@gmail.com>,
	Zi Yan <ziy@nvidia.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	lkp@lists.01.org,
	Kernel Page Reclaim v2 <page-reclaim@google.com>
Subject: Re: [page-reclaim] Re: [PATCH v2 00/16] Multigenerational LRU Framework
Date: Wed, 14 Apr 2021 08:58:56 -0700	[thread overview]
Message-ID: <CALvZod5jbmw5KPoxpwam212LzH0NJm_JXJ1uiUX2v1LvbRLB_Q@mail.gmail.com> (raw)
In-Reply-To: <93308ea276cfe7997c29ce7132516e830e8fec40.camel@surriel.com>

On Wed, Apr 14, 2021 at 6:52 AM Rik van Riel <riel@surriel.com> wrote:
>
> On Wed, 2021-04-14 at 16:27 +0800, Huang, Ying wrote:
> > Yu Zhao <yuzhao@google.com> writes:
> >
> > > On Wed, Apr 14, 2021 at 12:15 AM Huang, Ying <ying.huang@intel.com>
> > > wrote:
> > > >
> > > NUMA Optimization
> > > -----------------
> > > Support NUMA policies and per-node RSS counters.
> > >
> > > We only can move forward one step at a time. Fair?
> >
> > You don't need to implement that now definitely.  But we can discuss
> > the
> > possible solution now.
>
> That was my intention, too. I want to make sure we don't
> end up "painting ourselves into a corner" by moving in some
> direction we have no way to get out of.
>
> The patch set looks promising, but we need some plan to
> avoid the worst case behaviors that forced us into rmap
> based scanning initially.
>
> > Note that it's possible that only some processes are bound to some
> > NUMA
> > nodes, while other processes aren't bound.
>
> For workloads like PostgresQL or Oracle, it is common
> to have maybe 70% of memory in a large shared memory
> segment, spread between all the NUMA nodes, and mapped
> into hundreds, if not thousands, of processes in the
> system.
>
> Now imagine we have an 8 node system, and memory
> pressure in the DMA32 zone of node 0.
>
> How will the current VM behave?
>
> Wha
> t will the virtual scanning need to do?
>
> If we can come up with a solution to make virtual
> scanning scale for that kind of workload, great.
>
> If not ... if it turns out most of the benefits of
> the multigeneratinal LRU framework come from sorting
> the pages into multiple LRUs, and from being able
> to easily reclaim unmapped pages before having to
> scan mapped ones, could it be an idea to implement
> that first, independently from virtual scanning?
>
> I am all for improving
> our page reclaim system, I
> just want to make sure we don't revisit the old traps
> that forced us where we are today :)
>

One potential idea is to take the hybrid 'of rmap and virtual
scanning' approach. If the number of pages that are targeted to be
scanned is below some threshold, do rmap otherwise virtual scanning. I
think we can experimentally find good value for that threshold.

  parent reply	other threads:[~2021-04-14 15:59 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-13  6:56 Yu Zhao
2021-04-13  6:56 ` [PATCH v2 01/16] include/linux/memcontrol.h: do not warn in page_memcg_rcu() if !CONFIG_MEMCG Yu Zhao
2021-04-13  6:56 ` [PATCH v2 02/16] include/linux/nodemask.h: define next_memory_node() if !CONFIG_NUMA Yu Zhao
2021-04-13  6:56 ` [PATCH v2 03/16] include/linux/huge_mm.h: define is_huge_zero_pmd() if !CONFIG_TRANSPARENT_HUGEPAGE Yu Zhao
2021-04-13  6:56 ` [PATCH v2 04/16] include/linux/cgroup.h: export cgroup_mutex Yu Zhao
2021-04-13  6:56 ` [PATCH v2 05/16] mm/swap.c: export activate_page() Yu Zhao
2021-04-13  6:56 ` [PATCH v2 06/16] mm, x86: support the access bit on non-leaf PMD entries Yu Zhao
2021-04-13  6:56 ` [PATCH v2 07/16] mm/vmscan.c: refactor shrink_node() Yu Zhao
2021-04-13  6:56 ` [PATCH v2 08/16] mm: multigenerational lru: groundwork Yu Zhao
2021-04-13  6:56 ` [PATCH v2 09/16] mm: multigenerational lru: activation Yu Zhao
2021-04-13  6:56 ` [PATCH v2 10/16] mm: multigenerational lru: mm_struct list Yu Zhao
2021-04-14 14:36   ` Matthew Wilcox
2021-04-13  6:56 ` [PATCH v2 11/16] mm: multigenerational lru: aging Yu Zhao
2021-04-13  6:56 ` [PATCH v2 12/16] mm: multigenerational lru: eviction Yu Zhao
2021-04-13  6:56 ` [PATCH v2 13/16] mm: multigenerational lru: page reclaim Yu Zhao
2021-04-13  6:56 ` [PATCH v2 14/16] mm: multigenerational lru: user interface Yu Zhao
2021-04-13  6:56 ` [PATCH v2 15/16] mm: multigenerational lru: Kconfig Yu Zhao
2021-04-13  6:56 ` [PATCH v2 16/16] mm: multigenerational lru: documentation Yu Zhao
2021-04-13  7:51 ` [PATCH v2 00/16] Multigenerational LRU Framework SeongJae Park
2021-04-13 16:13   ` Jens Axboe
2021-04-13 16:42     ` SeongJae Park
2021-04-13 23:14     ` Dave Chinner
2021-04-14  2:29       ` Rik van Riel
     [not found]         ` <CAOUHufafMcaG8sOS=1YMy2P_6p0R1FzP16bCwpUau7g1-PybBQ@mail.gmail.com>
2021-04-14  6:15           ` Huang, Ying
2021-04-14  7:58             ` Yu Zhao
2021-04-14  8:27               ` Huang, Ying
2021-04-14 13:51                 ` Rik van Riel
2021-04-14 15:56                   ` Andi Kleen
2021-04-14 15:58                   ` Shakeel Butt [this message]
2021-04-14 18:45                   ` Yu Zhao
2021-04-14 15:51           ` Andi Kleen
2021-04-14 15:58             ` Rik van Riel
2021-04-14 19:14               ` Yu Zhao
2021-04-14 19:41                 ` Rik van Riel
2021-04-14 20:08                   ` Yu Zhao
2021-04-14 19:04             ` Yu Zhao
2021-04-15  3:00               ` Andi Kleen
2021-04-15  7:13                 ` Yu Zhao
2021-04-15  8:19                   ` Huang, Ying
2021-04-15  9:57                   ` Michel Lespinasse
2021-04-24  2:33                     ` Yu Zhao
2021-04-24  3:30                       ` Andi Kleen
2021-04-24  4:16                         ` Yu Zhao
2021-04-14  3:40       ` Yu Zhao
2021-04-14  4:50         ` Dave Chinner
2021-04-14  7:16           ` Yu Zhao
2021-04-14 10:00             ` Yu Zhao
2021-04-15  1:36             ` Dave Chinner
2021-04-24 21:21               ` Yu Zhao
2021-04-14 14:43       ` Jens Axboe
2021-04-14 19:42         ` Yu Zhao
2021-04-15  1:21         ` Dave Chinner
2021-04-14 17:43 ` Johannes Weiner
2021-04-27 10:35   ` Yu Zhao
2021-04-29 23:46 ` Konstantin Kharlamov
2021-04-30  6:37   ` Konstantin Kharlamov
2021-04-30 19:31     ` Yu Zhao

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