linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
From: Andrew Morton <akpm@linux-foundation.org>
To: Alex Shi <alex.shi@linux.alibaba.com>
Cc: cgroups@vger.kernel.org, mgorman@techsingularity.net,
	tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru,
	daniel.m.jordan@oracle.com, yang.shi@linux.alibaba.com,
	willy@infradead.org, hannes@cmpxchg.org, lkp@intel.com,
	Michal Hocko <mhocko@kernel.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v9 07/20] mm/lru: introduce TestClearPageLRU
Date: Tue, 3 Mar 2020 16:46:59 -0800	[thread overview]
Message-ID: <20200303164659.b3a30ab9d68c9ed82299a29c@linux-foundation.org> (raw)
In-Reply-To: <9cacdc21-9c1f-2a17-05cb-e9cf2959cef5@linux.alibaba.com>

On Tue, 3 Mar 2020 12:11:34 +0800 Alex Shi <alex.shi@linux.alibaba.com> wrote:

> 
> 
> 在 2020/3/3 上午6:11, Andrew Morton 写道:
> >> -		if (PageLRU(page)) {
> >> +		if (TestClearPageLRU(page)) {
> >>  			lruvec = mem_cgroup_page_lruvec(page, pgdat);
> >> -			ClearPageLRU(page);
> >>  			del_page_from_lru_list(page, lruvec, page_lru(page));
> >>  		} else
> > 
> > The code will now get exclusive access of the page->flags cacheline and
> > will dirty that cacheline, even for !PageLRU() pages.  What is the
> > performance impact of this?
> > 
> 
> Hi Andrew,
> 
> Thanks a lot for comments!
> 
> I was tested the whole patchset with fengguang's case-lru-file-readtwice
> https://git.kernel.org/pub/scm/linux/kernel/git/wfg/vm-scalability.git/
> which is most sensitive case on PageLRU I found. There are no clear performance
> drop.
> 
> On this single patch, I just test the same case again, there is still no perf
> drop. some data is here on my 96 threads machine:
> 
> 		no lock_dep	w lock_dep and few other debug option
> w this patch, 	50.96MB/s		32.93MB/s
> w/o this patch, 50.50MB/s		33.53MB/s
> 
> 

Well, any difference would be small and the numbers did get a bit
lower, albeit probably within the margin of error.

But you know, if someone were to send a patch which micro-optimized
some code by replacing 'TestClearXXX()' with `if PageXXX()
ClearPageXXX()', I would happily merge it!

Is this change essential to the overall patchset?  If not, I'd be
inclined to skip it?



  reply	other threads:[~2020-03-04  0:47 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1583146830-169516-1-git-send-email-alex.shi@linux.alibaba.com>
2020-03-02 11:00 ` [PATCH v9 01/20] mm/vmscan: remove unnecessary lruvec adding Alex Shi
2020-03-02 11:00 ` [PATCH v9 02/20] mm/memcg: fold lock_page_lru into commit_charge Alex Shi
2020-03-02 11:00 ` [PATCH v9 03/20] mm/page_idle: no unlikely double check for idle page counting Alex Shi
2020-03-02 11:00 ` [PATCH v9 04/20] mm/thp: move lru_add_page_tail func to huge_memory.c Alex Shi
2020-03-04  7:47   ` Kirill A. Shutemov
2020-03-04  8:13     ` Alex Shi
2020-03-02 11:00 ` [PATCH v9 05/20] mm/thp: clean up lru_add_page_tail Alex Shi
2020-03-02 11:00 ` [PATCH v9 06/20] mm/thp: narrow lru locking Alex Shi
2020-03-04  8:02   ` Kirill A. Shutemov
2020-03-04  8:51     ` Alex Shi
2020-03-02 11:00 ` [PATCH v9 07/20] mm/lru: introduce TestClearPageLRU Alex Shi
2020-03-02 22:11   ` Andrew Morton
2020-03-03  4:11     ` Alex Shi
2020-03-04  0:46       ` Andrew Morton [this message]
2020-03-04  7:06         ` Alex Shi
2020-03-04  9:03           ` Rong Chen
2020-03-04  9:37             ` Alex Shi
2020-03-02 11:00 ` [PATCH v9 08/20] mm/lru: add page isolation precondition in __isolate_lru_page Alex Shi
2020-03-02 11:00 ` [PATCH v9 09/20] mm/mlock: ClearPageLRU before get lru lock in munlock page isolation Alex Shi
2020-03-02 11:00 ` [PATCH v9 10/20] mm/lru: take PageLRU first in moving page between lru lists Alex Shi
2020-03-02 11:00 ` [PATCH v9 11/20] mm/memcg: move SetPageLRU out of lru_lock in commit_charge Alex Shi
2020-03-02 11:00 ` [PATCH v9 12/20] mm/mlock: clean up __munlock_isolate_lru_page Alex Shi
2020-03-02 11:00 ` [PATCH v9 13/20] mm/lru: replace pgdat lru_lock with lruvec lock Alex Shi
2020-03-02 11:00 ` [PATCH v9 14/20] mm/lru: introduce the relock_page_lruvec function Alex Shi
2020-03-02 11:00 ` [PATCH v9 15/20] mm/mlock: optimize munlock_pagevec by relocking Alex Shi
2020-03-02 11:00 ` [PATCH v9 16/20] mm/swap: only change the lru_lock iff page's lruvec is different Alex Shi
2020-03-02 11:00 ` [PATCH v9 17/20] mm/pgdat: remove pgdat lru_lock Alex Shi
2020-03-02 11:00 ` [PATCH v9 18/20] mm/lru: revise the comments of lru_lock Alex Shi
2020-03-02 11:00 ` [PATCH v9 19/20] mm/lru: add debug checking for page memcg moving Alex Shi
2020-03-02 11:00 ` [PATCH v9 20/20] mm/memcg: add debug checking in lock_page_memcg Alex Shi
2020-03-04  3:13 ` [PATCH v9 02/20] mm/memcg: fold lock_page_lru into commit_charge Hillf Danton
2020-03-04  7:19   ` Alex Shi

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=20200303164659.b3a30ab9d68c9ed82299a29c@linux-foundation.org \
    --to=akpm@linux-foundation.org \
    --cc=alex.shi@linux.alibaba.com \
    --cc=cgroups@vger.kernel.org \
    --cc=daniel.m.jordan@oracle.com \
    --cc=hannes@cmpxchg.org \
    --cc=hughd@google.com \
    --cc=khlebnikov@yandex-team.ru \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=lkp@intel.com \
    --cc=mgorman@techsingularity.net \
    --cc=mhocko@kernel.org \
    --cc=tj@kernel.org \
    --cc=vdavydov.dev@gmail.com \
    --cc=willy@infradead.org \
    --cc=yang.shi@linux.alibaba.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).