From: Yu Zhao <yuzhao@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Stephen Rothwell" <sfr@rothwell.id.au>,
Linux-MM <linux-mm@kvack.org>, "Andi Kleen" <ak@linux.intel.com>,
"Aneesh Kumar" <aneesh.kumar@linux.ibm.com>,
"Barry Song" <21cnbao@gmail.com>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Hillf Danton" <hdanton@sina.com>, "Jens Axboe" <axboe@kernel.dk>,
"Jesse Barnes" <jsbarnes@google.com>,
"Johannes Weiner" <hannes@cmpxchg.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Matthew Wilcox" <willy@infradead.org>,
"Mel Gorman" <mgorman@suse.de>,
"Michael Larabel" <Michael@michaellarabel.com>,
"Michal Hocko" <mhocko@kernel.org>,
"Mike Rapoport" <rppt@kernel.org>,
"Rik van Riel" <riel@surriel.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Will Deacon" <will@kernel.org>,
"Ying Huang" <ying.huang@intel.com>,
"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
"Kernel Page Reclaim v2" <page-reclaim@google.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
"Brian Geffon" <bgeffon@google.com>,
"Jan Alexander Steffens" <heftig@archlinux.org>,
"Oleksandr Natalenko" <oleksandr@natalenko.name>,
"Steven Barrett" <steven@liquorix.net>,
"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>,
"Vaibhav Jain" <vaibhav@linux.ibm.com>
Subject: Re: [PATCH v10 12/14] mm: multi-gen LRU: debugfs interface
Date: Tue, 26 Apr 2022 16:15:26 -0600 [thread overview]
Message-ID: <CAOUHufY1FmZGnAvpRYtTvXQ2cYTisxUauD0MzSXDesQ-T6GvQg@mail.gmail.com> (raw)
In-Reply-To: <20220426143034.f520c062830f9e3405c890d0@linux-foundation.org>
On Tue, Apr 26, 2022 at 3:30 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Tue, 26 Apr 2022 00:59:37 -0600 Yu Zhao <yuzhao@google.com> wrote:
>
> > On Fri, Apr 15, 2022 at 10:20 PM Andrew Morton
> > <akpm@linux-foundation.org> wrote:
> > >
> > > On Fri, 15 Apr 2022 18:03:16 -0600 Yu Zhao <yuzhao@google.com> wrote:
> > >
> > > > > Presumably sysfs is the place. Fully documented and with usage
> > > > > examples in the changelog so we can carefully review the proposed
> > > > > extensions to Linux's ABI. Extensions which must be maintained
> > > > > unchanged for all time.
> > > >
> > > > Eventually, yes. There still is a long way to go. Rest assured, this
> > > > is something Google will keep investing resources on.
> > >
> > > So. The plan is to put these interfaces in debugfs for now, with a
> > > view to migrating stabilized interfaces into sysfs (or procfs or
> > > whatever) once end-user requirements and use cases are better
> > > understood?
> >
> > The requirements are well understood and the use cases are proven,
> > e.g., Google [1], Meta [2] and Alibaba [3].
> >
> > [1] https://dl.acm.org/doi/10.1145/3297858.3304053
> > [2] https://dl.acm.org/doi/10.1145/3503222.3507731
> > [3] https://gitee.com/anolis/cloud-kernel/blob/release-5.10/mm/kidled.c
>
> So will these interfaces be moved into sysfs?
So the debugfs interface from this patch provides:
1. proactive reclaim,
2. working set estimation.
The sysfs interface for item 1 is being finalized by [4], and it's a
subset of this debugfs interface because we want it to be more
general. The sysfs interface for item 2 will be eventually proposed as
well, with the same approach. It will look like a histogram in which
the active/inactive LRU has two bins whereas MGLRU has more bins. Bins
contain pages and multiple bins represent different hotness/coldness.
Since [4] took about two years, I'd say this histogram-like interface
would take no less than a couple of years as well.
This debugfs interface stays even after that, and it will serve its
true purpose (debugging), not a substitute for the sysfs interfaces.
> > > If so, that sounds totally great to me. But it should have been in
> > > the darn changelog! This is the sort of thing which we care about most
> > > keenly.
> > >
> > > It would be helpful for reviewers to understand the proposed timeline
> > > for this process, because the entire feature isn't really real until
> > > this is completed, is it? I do think we should get this nailed down
> > > relatively rapidly, otherwise people will be reluctant to invest much
> > > into a moving target.
> > >
> > > And I must say, I see dissonance between the overall maturity of the
> > > feature as described in these emails versus the immaturity of these
> > > userspace control interfaces. What's happening there?
> >
> > Very observant. To answer both of the questions above: each iteration
> > of the entire stack is a multi-year effort.
> >
> > Given its ROI, companies I know of constantly pour money into this
> > area. Given its scale, this debugfs is the least of their concerns. A
> > good example is the proactive reclaim sysfs interface [4]. It's been
> > used at Google for many years and at Meta for a few years. We only
> > started finalizing it recently.
> >
> > [4] https://lore.kernel.org/r/20220425190040.2475377-1-yosryahmed@google.com/
>
> Sure, if one organization is involved in both the userspace code and
> the kernel interfaces then the alteration of kernel interfaces can be
> handled in a coordinated fashion.
>
> But releasing interfaces to the whole world is a different deal. It's
> acceptable to say "this is in debugfs for now because it's a work
> in progress" but it sounds like mglru's interfaces are beyond that
> stage?
Correct. It's a WIP in the sense of "know what needs to be done but
can't get it done immediately", not "don't know what's next; try this
for now".
next prev parent reply other threads:[~2022-04-26 22:16 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-07 3:15 [PATCH v10 00/14] Multi-Gen LRU Framework Yu Zhao
2022-04-07 3:15 ` [PATCH v10 01/14] mm: x86, arm64: add arch_has_hw_pte_young() Yu Zhao
2022-04-07 3:15 ` [PATCH v10 02/14] mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG Yu Zhao
2022-04-07 3:15 ` [PATCH v10 03/14] mm/vmscan.c: refactor shrink_node() Yu Zhao
2022-04-16 6:48 ` Miaohe Lin
2022-04-07 3:15 ` [PATCH v10 04/14] Revert "include/linux/mm_inline.h: fold __update_lru_size() into its sole caller" Yu Zhao
2022-04-16 6:50 ` Miaohe Lin
2022-04-07 3:15 ` [PATCH v10 05/14] mm: multi-gen LRU: groundwork Yu Zhao
2022-04-12 2:16 ` Andrew Morton
2022-04-12 7:06 ` Peter Zijlstra
2022-04-20 0:39 ` Yu Zhao
2022-04-20 20:07 ` Linus Torvalds
2022-04-26 22:39 ` Yu Zhao
2022-04-26 23:42 ` Andrew Morton
2022-04-27 1:18 ` Yu Zhao
2022-04-27 1:34 ` Andrew Morton
2022-04-07 3:15 ` [PATCH v10 06/14] mm: multi-gen LRU: minimal implementation Yu Zhao
2022-04-14 6:03 ` Barry Song
2022-04-14 20:36 ` Yu Zhao
2022-04-14 21:39 ` Andrew Morton
2022-04-14 22:14 ` Yu Zhao
2022-04-15 10:15 ` Barry Song
2022-04-15 20:17 ` Yu Zhao
2022-04-15 10:26 ` Barry Song
2022-04-15 20:18 ` Yu Zhao
[not found] ` <71af92d2-0777-c318-67fb-8f7d52c800bb@huawei.com>
2022-04-14 20:53 ` Yu Zhao
2022-04-15 2:23 ` Chen Wandun
2022-04-15 5:25 ` Yu Zhao
2022-04-15 6:31 ` Chen Wandun
2022-04-15 6:44 ` Yu Zhao
2022-04-15 9:27 ` Chen Wandun
2022-04-18 9:58 ` Barry Song
2022-04-19 0:53 ` Yu Zhao
2022-04-19 4:25 ` Barry Song
2022-04-19 4:36 ` Barry Song
2022-04-19 22:25 ` Yu Zhao
2022-04-19 22:20 ` Yu Zhao
2022-04-07 3:15 ` [PATCH v10 07/14] mm: multi-gen LRU: exploit locality in rmap Yu Zhao
2022-04-27 4:32 ` Aneesh Kumar K.V
2022-04-27 4:38 ` Yu Zhao
2022-04-27 5:31 ` Aneesh Kumar K V
2022-04-27 6:00 ` Yu Zhao
2022-04-07 3:15 ` [PATCH v10 08/14] mm: multi-gen LRU: support page table walks Yu Zhao
2022-04-12 2:16 ` Andrew Morton
2022-04-12 7:10 ` Peter Zijlstra
2022-04-15 5:30 ` Yu Zhao
2022-04-15 1:14 ` Yu Zhao
2022-04-15 1:56 ` Andrew Morton
2022-04-15 6:25 ` Yu Zhao
2022-04-15 19:15 ` Andrew Morton
2022-04-15 20:11 ` Yu Zhao
2022-04-15 21:32 ` Andrew Morton
2022-04-15 21:36 ` Linus Torvalds
2022-04-15 22:57 ` Yu Zhao
2022-04-15 23:03 ` Linus Torvalds
2022-04-15 23:24 ` [page-reclaim] " Jesse Barnes
2022-04-15 23:31 ` Matthew Wilcox
2022-04-15 23:37 ` Jesse Barnes
2022-04-15 23:49 ` Yu Zhao
2022-04-16 16:32 ` Justin Forbes
2022-04-19 22:32 ` Yu Zhao
2022-04-29 14:10 ` zhong jiang
2022-04-30 8:34 ` Yu Zhao
2022-04-07 3:15 ` [PATCH v10 09/14] mm: multi-gen LRU: optimize multiple memcgs Yu Zhao
2022-04-07 3:15 ` [PATCH v10 10/14] mm: multi-gen LRU: kill switch Yu Zhao
2022-04-12 2:16 ` Andrew Morton
2022-04-26 20:57 ` Yu Zhao
2022-04-26 22:22 ` Andrew Morton
2022-04-27 1:11 ` Yu Zhao
2022-04-07 3:15 ` [PATCH v10 11/14] mm: multi-gen LRU: thrashing prevention Yu Zhao
2022-04-07 3:15 ` [PATCH v10 12/14] mm: multi-gen LRU: debugfs interface Yu Zhao
2022-04-12 2:16 ` Andrew Morton
2022-04-16 0:03 ` Yu Zhao
2022-04-16 4:20 ` Andrew Morton
2022-04-26 6:59 ` Yu Zhao
2022-04-26 21:30 ` Andrew Morton
2022-04-26 22:15 ` Yu Zhao [this message]
2022-04-07 3:15 ` [PATCH v10 13/14] mm: multi-gen LRU: admin guide Yu Zhao
2022-04-07 12:41 ` Bagas Sanjaya
2022-04-07 12:51 ` Jonathan Corbet
2022-04-12 2:16 ` Andrew Morton
2022-04-16 2:22 ` Yu Zhao
2022-04-07 3:15 ` [PATCH v10 14/14] mm: multi-gen LRU: design doc Yu Zhao
2022-04-07 11:39 ` Huang Shijie
2022-04-07 12:41 ` Bagas Sanjaya
2022-04-07 12:52 ` Jonathan Corbet
2022-04-08 4:48 ` Bagas Sanjaya
2022-04-12 2:16 ` Andrew Morton
2022-04-26 7:42 ` Yu Zhao
2022-04-07 3:24 ` [PATCH v10 00/14] Multi-Gen LRU Framework Yu Zhao
2022-04-07 8:31 ` Stephen Rothwell
2022-04-07 9:08 ` Yu Zhao
2022-04-07 9:41 ` Yu Zhao
2022-04-07 12:13 ` Stephen Rothwell
2022-04-08 2:08 ` Yu Zhao
2022-04-12 2:15 ` Andrew Morton
2022-04-14 5:06 ` Andrew Morton
2022-04-20 0:50 ` Yu Zhao
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 \
--in-reply-to=CAOUHufY1FmZGnAvpRYtTvXQ2cYTisxUauD0MzSXDesQ-T6GvQg@mail.gmail.com \
--to=yuzhao@google.com \
--cc=21cnbao@gmail.com \
--cc=Hi-Angel@yandex.ru \
--cc=Michael@michaellarabel.com \
--cc=ak@linux.intel.com \
--cc=akpm@linux-foundation.org \
--cc=aneesh.kumar@linux.ibm.com \
--cc=axboe@kernel.dk \
--cc=bgeffon@google.com \
--cc=catalin.marinas@arm.com \
--cc=corbet@lwn.net \
--cc=d@chaos-reins.com \
--cc=dave.hansen@linux.intel.com \
--cc=djbyrne@mtu.edu \
--cc=hannes@cmpxchg.org \
--cc=hdanton@sina.com \
--cc=heftig@archlinux.org \
--cc=holger@applied-asynchrony.com \
--cc=jsbarnes@google.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=mhocko@kernel.org \
--cc=oleksandr@natalenko.name \
--cc=page-reclaim@google.com \
--cc=riel@surriel.com \
--cc=rppt@kernel.org \
--cc=sfr@rothwell.id.au \
--cc=sofia.trinh@edi.works \
--cc=steven@liquorix.net \
--cc=suleiman@google.com \
--cc=szhai2@cs.rochester.edu \
--cc=torvalds@linux-foundation.org \
--cc=vaibhav@linux.ibm.com \
--cc=vbabka@suse.cz \
--cc=will@kernel.org \
--cc=willy@infradead.org \
--cc=x86@kernel.org \
--cc=ying.huang@intel.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).