From: Yu Zhao <yuzhao@google.com>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
"Johannes Weiner" <hannes@cmpxchg.org>,
"Mel Gorman" <mgorman@suse.de>,
"Michal Hocko" <mhocko@kernel.org>,
"Andi Kleen" <ak@linux.intel.com>,
"Aneesh Kumar" <aneesh.kumar@linux.ibm.com>,
"Barry Song" <21cnbao@gmail.com>,
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"Linus Torvalds" <torvalds@linux-foundation.org>,
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"Brian Geffon" <bgeffon@google.com>,
"Jan Alexander Steffens" <heftig@archlinux.org>,
"Oleksandr Natalenko" <oleksandr@natalenko.name>,
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"Suleiman Souhlal" <suleiman@google.com>,
"Daniel Byrne" <djbyrne@mtu.edu>,
"Donald Carr" <d@chaos-reins.com>,
"Holger Hoffstätte" <holger@applied-asynchrony.com>,
"Konstantin Kharlamov" <Hi-Angel@yandex.ru>,
"Shuang Zhai" <szhai2@cs.rochester.edu>,
"Sofia Trinh" <sofia.trinh@edi.works>
Subject: Re: [PATCH v7 05/12] mm: multigenerational LRU: minimal implementation
Date: Wed, 23 Feb 2022 18:34:33 -0700 [thread overview]
Message-ID: <CAOUHufY8dRimricP=pvvgg8mEagb369nE8MVe6tnnLXQuKyAEA@mail.gmail.com> (raw)
In-Reply-To: <87y2213wrl.fsf@yhuang6-desk2.ccr.corp.intel.com>
On Wed, Feb 23, 2022 at 5:59 PM Huang, Ying <ying.huang@intel.com> wrote:
>
> Yu Zhao <yuzhao@google.com> writes:
>
> > On Wed, Feb 23, 2022 at 1:28 AM Huang, Ying <ying.huang@intel.com> wrote:
> >>
> >> Hi, Yu,
> >>
> >> Yu Zhao <yuzhao@google.com> writes:
> >>
> >> > To avoid confusions, the terms "promotion" and "demotion" will be
> >> > applied to the multigenerational LRU, as a new convention; the terms
> >> > "activation" and "deactivation" will be applied to the active/inactive
> >> > LRU, as usual.
> >>
> >> In the memory tiering related commits and patchset, for example as follows,
> >>
> >> commit 668e4147d8850df32ca41e28f52c146025ca45c6
> >> Author: Yang Shi <yang.shi@linux.alibaba.com>
> >> Date: Thu Sep 2 14:59:19 2021 -0700
> >>
> >> mm/vmscan: add page demotion counter
> >>
> >> https://lore.kernel.org/linux-mm/20220221084529.1052339-1-ying.huang@intel.com/
> >>
> >> "demote" and "promote" is used for migrating pages between different
> >> types of memory. Is it better for us to avoid overloading these words
> >> too much to avoid the possible confusion?
> >
> > Given that LRU and migration are usually different contexts, I think
> > we'd be fine, unless we want a third pair of terms.
>
> This is true before memory tiering is introduced. In systems with
> multiple types memory (called memory tiering), LRU is used to identify
> pages to be migrated to the slow memory node. Please take a look at
> can_demote(), which is called in shrink_page_list().
This sounds clearly two contexts to me. Promotion/demotion (move
between generations) while pages are on LRU; or promotion/demotion
(migration between nodes) after pages are taken off LRU.
Note that promotion/demotion are not used in function names. They are
used to describe how MGLRU works, in comparison with the
active/inactive LRU. Memory tiering is not within this context.
> >> > +static int get_swappiness(struct mem_cgroup *memcg)
> >> > +{
> >> > + return mem_cgroup_get_nr_swap_pages(memcg) >= MIN_LRU_BATCH ?
> >> > + mem_cgroup_swappiness(memcg) : 0;
> >> > +}
> >>
> >> After we introduced demotion support in Linux kernel. The anonymous
> >> pages in the fast memory node could be demoted to the slow memory node
> >> via the page reclaiming mechanism as in the following commit. Can you
> >> consider that too?
> >
> > Sure. How do I check whether there is still space on the slow node?
>
> You can always check the watermark of the slow node. But now, we
> actually don't check that (as in demote_page_list()), instead we will
> wake up kswapd of the slow node. The intended behavior is something
> like,
>
> DRAM -> PMEM -> disk
I'll look into this later -- for now, it's a low priority because
there isn't much demand. I'll bump it up if anybody is interested in
giving it a try. Meanwhile, please feel free to cook up something if
you are interested.
next prev parent reply other threads:[~2022-02-24 1:34 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-08 8:18 [PATCH v7 00/12] Multigenerational LRU Framework Yu Zhao
2022-02-08 8:18 ` [PATCH v7 01/12] mm: x86, arm64: add arch_has_hw_pte_young() Yu Zhao
2022-02-08 8:24 ` Yu Zhao
2022-02-08 10:33 ` Will Deacon
2022-02-08 8:18 ` [PATCH v7 02/12] mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG Yu Zhao
2022-02-08 8:27 ` Yu Zhao
2022-02-08 8:18 ` [PATCH v7 03/12] mm/vmscan.c: refactor shrink_node() Yu Zhao
2022-02-08 8:18 ` [PATCH v7 04/12] mm: multigenerational LRU: groundwork Yu Zhao
2022-02-08 8:28 ` Yu Zhao
2022-02-10 20:41 ` Johannes Weiner
2022-02-15 9:43 ` Yu Zhao
2022-02-15 21:53 ` Johannes Weiner
2022-02-21 8:14 ` Yu Zhao
2022-02-23 21:18 ` Yu Zhao
2022-02-25 16:34 ` Minchan Kim
2022-03-03 15:29 ` Johannes Weiner
2022-03-03 19:26 ` Yu Zhao
2022-03-03 21:43 ` Johannes Weiner
2022-03-11 10:16 ` Barry Song
2022-03-11 23:45 ` Yu Zhao
2022-03-12 10:37 ` Barry Song
2022-03-12 21:11 ` Yu Zhao
2022-03-13 4:57 ` Barry Song
2022-03-14 11:11 ` Barry Song
2022-03-14 16:45 ` Yu Zhao
2022-03-14 23:38 ` Barry Song
[not found] ` <CAOUHufa9eY44QadfGTzsxa2=hEvqwahXd7Canck5Gt-N6c4UKA@mail.gmail.com>
[not found] ` <CAGsJ_4zvj5rmz7DkW-kJx+jmUT9G8muLJ9De--NZma9ey0Oavw@mail.gmail.com>
2022-03-15 10:29 ` Barry Song
2022-03-16 2:46 ` Yu Zhao
2022-03-16 4:37 ` Barry Song
2022-03-16 5:44 ` Yu Zhao
2022-03-16 6:06 ` Barry Song
2022-03-16 21:37 ` Yu Zhao
2022-02-10 21:37 ` Matthew Wilcox
2022-02-13 21:16 ` Yu Zhao
2022-02-08 8:18 ` [PATCH v7 05/12] mm: multigenerational LRU: minimal implementation Yu Zhao
2022-02-08 8:33 ` Yu Zhao
2022-02-08 16:50 ` Johannes Weiner
2022-02-10 2:53 ` Yu Zhao
2022-02-13 10:04 ` Hillf Danton
2022-02-17 0:13 ` Yu Zhao
2022-02-23 8:27 ` Huang, Ying
2022-02-23 9:36 ` Yu Zhao
2022-02-24 0:59 ` Huang, Ying
2022-02-24 1:34 ` Yu Zhao [this message]
2022-02-24 3:31 ` Huang, Ying
2022-02-24 4:09 ` Yu Zhao
2022-02-24 5:27 ` Huang, Ying
2022-02-24 5:35 ` Yu Zhao
2022-02-08 8:18 ` [PATCH v7 06/12] mm: multigenerational LRU: exploit locality in rmap Yu Zhao
2022-02-08 8:40 ` Yu Zhao
2022-02-08 8:18 ` [PATCH v7 07/12] mm: multigenerational LRU: support page table walks Yu Zhao
2022-02-08 8:39 ` Yu Zhao
2022-02-08 8:18 ` [PATCH v7 08/12] mm: multigenerational LRU: optimize multiple memcgs Yu Zhao
2022-02-08 8:18 ` [PATCH v7 09/12] mm: multigenerational LRU: runtime switch Yu Zhao
2022-02-08 8:42 ` Yu Zhao
2022-02-08 8:19 ` [PATCH v7 10/12] mm: multigenerational LRU: thrashing prevention Yu Zhao
2022-02-08 8:43 ` Yu Zhao
2022-02-08 8:19 ` [PATCH v7 11/12] mm: multigenerational LRU: debugfs interface Yu Zhao
2022-02-18 18:56 ` [page-reclaim] " David Rientjes
2022-02-08 8:19 ` [PATCH v7 12/12] mm: multigenerational LRU: documentation Yu Zhao
2022-02-08 8:44 ` Yu Zhao
2022-02-14 10:28 ` Mike Rapoport
2022-02-16 3:22 ` Yu Zhao
2022-02-21 9:01 ` Mike Rapoport
2022-02-22 1:47 ` Yu Zhao
2022-02-23 10:58 ` Mike Rapoport
2022-02-23 21:20 ` Yu Zhao
2022-02-08 10:11 ` [PATCH v7 00/12] Multigenerational LRU Framework Oleksandr Natalenko
2022-02-08 11:14 ` Michal Hocko
2022-02-08 11:23 ` Oleksandr Natalenko
2022-02-11 20:12 ` Alexey Avramov
2022-02-12 21:01 ` Yu Zhao
2022-03-03 6:06 ` Vaibhav Jain
2022-03-03 6:47 ` Yu Zhao
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