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From: "Huang, Ying" <ying.huang@intel.com>
To: Yu Zhao <yuzhao@google.com>
Cc: Rik van Riel <riel@surriel.com>,
	Dave Chinner <david@fromorbit.com>, Jens Axboe <axboe@kernel.dk>,
	SeongJae Park <sj38.park@gmail.com>,
	Linux-MM <linux-mm@kvack.org>,
	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>,
	Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH v2 00/16] Multigenerational LRU Framework
Date: Thu, 15 Apr 2021 16:19:52 +0800	[thread overview]
Message-ID: <87a6q0ot7b.fsf@yhuang6-desk1.ccr.corp.intel.com> (raw)
In-Reply-To: <CAOUHufaAz72+0HJu=XPv-6T8rUAdYo_mb5=H+yF3=LfwoufeYg@mail.gmail.com> (Yu Zhao's message of "Thu, 15 Apr 2021 01:13:13 -0600")

Yu Zhao <yuzhao@google.com> writes:

> On Wed, Apr 14, 2021 at 9:00 PM Andi Kleen <ak@linux.intel.com> wrote:
>>
>> > We fall back to the rmap when it's obviously not smart to do so. There
>> > is still a lot of room for improvement in this function though, i.e.,
>> > it should be per VMA and NUMA aware.
>>
>> Okay so it's more a question to tune the cross over heuristic. That
>> sounds much easier than replacing everything.
>>
>> Of course long term it might be a problem to maintain too many
>> different ways to do things, but I suppose short term it's a reasonable
>> strategy.
>
> Hi Rik, Ying,
>
> Sorry for being persistent. I want to make sure we are on the same page:
>
> Page table scanning doesn't replace the existing rmap walk. It is
> complementary and only happens when it is likely that most of the
> pages on a system under pressure have been referenced, i.e., out of
> *inactive* pages, by definition of the existing implementation. Under
> such a condition, scanning *active* pages one by one with the rmap is
> likely to cost more than scanning them all at once via page tables.
> When we evict *inactive* pages, we still use the rmap and share a
> common path with the existing code.
>
> Page table scanning falls back to the rmap walk if the page tables of
> a process are apparently sparse, i.e., rss < size of the page tables.
>
> I should have clarified this at the very beginning of the discussion.
> But it has become so natural to me and I assumed we'd all see it this
> way.
>
> Your concern regarding the NUMA optimization is still valid, and it's
> a high priority.

Hi, Yu,

In general, I think it's a good idea to combine the page table scanning
and rmap scanning in the page reclaiming.  For example, if the
working-set is transitioned, we can take advantage of the fast page
table scanning to identify the new working-set quickly.  While we can
fallback to the rmap scanning if the page table scanning doesn't help.

Best Regards,
Huang, Ying

  reply	other threads:[~2021-04-15  8:20 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                   ` [page-reclaim] " Shakeel Butt
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 [this message]
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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