linux-kernel - Re: [PATCH] mm/vmscan.c: fix an implementation flaw in proportional scanning

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Message-ID: <1403082532.9368.4.camel@debian>
Date:	Wed, 18 Jun 2014 17:08:52 +0800
From:	Chen Yucong <slaoub@...il.com>
To:	Jerome Marchand <jmarchan@...hat.com>
Cc:	akpm@...ux-foundation.org, minchan@...nel.org, mgorman@...e.de,
	hannes@...xchg.org, mhocko@...e.cz, riel@...hat.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/vmscan.c: fix an implementation flaw in proportional
 scanning

On Wed, 2014-06-18 at 11:00 +0200, Jerome Marchand wrote:
> >               if (!nr_file || !nr_anon)
> >                       break;
> >  
> > -             if (nr_file > nr_anon) {
> > -                     unsigned long scan_target =
> targets[LRU_INACTIVE_ANON] +
> >
> -                                             targets[LRU_ACTIVE_ANON]
> + 1;
> > +             file_percent = nr_file * 100 / file_target;
> > +             anon_percent = nr_anon * 100 / anon_target;
> 
> Here it could happen.
> 
> 
The snippet 
	...
               if (!nr_file || !nr_anon)
                      break;
        ...
 can help us to filter the situation which you have described. It comes
from Mel's patch that is called:

mm: vmscan: use proportional scanning during direct reclaim and full
scan at DEF_PRIORITY

thx!
cyc

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