linux-kernel - Re: [PATCH v2] delayacct: track delays from write-protect copy

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Message-ID: <62514455.1c69fb81.5db1c.0ef7@mx.google.com>
Date:   Sat, 9 Apr 2022 08:31:14 +0000
From:   CGEL <cgel.zte@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     akpm@...ux-foundation.org, david@...hat.com, corbet@....net,
        bsingharora@...il.com, mike.kravetz@...cle.com,
        yang.yang29@....com.cn, wang.yong12@....com.cn,
        ran.xiaokai@....com.cn, jiang.xuexin@....com.cn,
        thomas.orgis@...-hamburg.de, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        sfr@...b.auug.org.au
Subject: Re: [PATCH v2] delayacct: track delays from write-protect copy

On Sat, Apr 09, 2022 at 09:53:09AM +0200, Peter Zijlstra wrote:
> On Sat, Apr 09, 2022 at 01:43:44AM +0000, cgel.zte@...il.com wrote:
> > From: Yang Yang <yang.yang29@....com.cn>
> > 
> > Delay accounting does not track the delay of write-protect copy. When
> > tasks trigger many write-protect copys(include COW and unsharing of
> > anonymous pages[1]), it may spend a amount of time waiting for them.
> > To get the delay of tasks in write-protect copy, could help users to
> > evaluate the impact of using KSM or fork() or GUP.
> > 
> > Also update tools/accounting/getdelays.c:
> > 
> >     / # ./getdelays -dl -p 231
> >     print delayacct stats ON
> >     listen forever
> >     PID     231
> > 
> >     CPU             count     real total  virtual total    delay total  delay average
> >                      6247     1859000000     2154070021     1674255063          0.268ms
> >     IO              count    delay total  delay average
> >                         0              0              0ms
> >     SWAP            count    delay total  delay average
> >                         0              0              0ms
> >     RECLAIM         count    delay total  delay average
> >                         0              0              0ms
> >     THRASHING       count    delay total  delay average
> >                         0              0              0ms
> >     COMPACT         count    delay total  delay average
> >                         3          72758              0ms
> >     WPCOPY          count    delay total  delay average
> >                      3635      271567604              0ms
> > 
> > [1] commit 31cc5bc4af70("mm: support GUP-triggered unsharing of anonymous pages")
> > 
> > Signed-off-by: Yang Yang <yang.yang29@....com.cn>
> > Reviewed-by: David Hildenbrand <david@...hat.com>
> > Reviewed-by: Jiang Xuexin <jiang.xuexin@....com.cn>
> > Reviewed-by: Ran Xiaokai <ran.xiaokai@....com.cn>
> > Reviewed-by: wangyong <wang.yong12@....com.cn>
> 
> As per always; I refuse to take patches from cgel.zte@...il.com. Because
> yet again From and Sender don't match.
> 
> If you want me to consider your email, please send from the email
> address you've listed in your SoB.
Very sorry to have this problem, because our company's mail system
(xx.zte.com.cn)has a little format problem, so we use gmail instead.

We do want to do a little work for the community, so sent patches
before it fixed. I will try to connect our mail system administrator
to solve it next time.

For this patch, it had been modified for several times, special thanks
to David Hildenbrand, so we hope to merge it(if no other problem).

Thanks!