Re: [patch] mm, vmscan: avoid thrashing anon lru when free + file is low

From	Minchan Kim <minchan@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [patch] mm, vmscan: avoid thrashing anon lru when free + file is low
Date	2017-04-20 08:10 +0200
Message-ID	<tydrX-5iV-3@gated-at.bofh.it> (permalink)
References	<txoSu-7uv-7@gated-at.bofh.it> <txqhz-8es-3@gated-at.bofh.it> <txJ0S-2KJ-15@gated-at.bofh.it> <txLvH-4wZ-11@gated-at.bofh.it> <ty7cR-1dY-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

Hi David,

On Wed, Apr 19, 2017 at 04:24:48PM -0700, David Rientjes wrote:
> On Wed, 19 Apr 2017, Minchan Kim wrote:
> 
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 24efcc20af91..5d2f3fa41e92 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -2174,8 +2174,17 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
> >  		}
> >  
> >  		if (unlikely(pgdatfile + pgdatfree <= total_high_wmark)) {
> > -			scan_balance = SCAN_ANON;
> > -			goto out;
> > +			/*
> > +			 * force SCAN_ANON if inactive anonymous LRU lists of
> > +			 * eligible zones are enough pages. Otherwise, thrashing
> > +			 * can be happen on the small anonymous LRU list.
> > +			 */
> > +			if (!inactive_list_is_low(lruvec, false, NULL, sc, false) &&
> > +			     lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, sc->reclaim_idx)
> > +					>> sc->priority) {
> > +				scan_balance = SCAN_ANON;
> > +				goto out;
> > +			}
> >  		}
> >  	}
> >  
> 
> Hi Minchan,
> 
> This looks good and it correctly biases against SCAN_ANON for my workload 
> that was thrashing the anon lrus.  Feel free to use parts of my changelog 
> if you'd like.

Thanks for the testing!
As considering how it's hard to find such a problem, it should be totally your
credit. So you can send the patch with detailed description. Feel free to
add my suggested-by. :)

Thanks!

Thread

[patch] mm, vmscan: avoid thrashing anon lru when free + file is  low David Rientjes <rientjes@google.com> - 2017-04-18 02:10 +0200
  Re: [patch] mm, vmscan: avoid thrashing anon lru when free + file is  low Minchan Kim <minchan@kernel.org> - 2017-04-18 03:40 +0200
    Re: [patch] mm, vmscan: avoid thrashing anon lru when free + file  is low David Rientjes <rientjes@google.com> - 2017-04-18 23:40 +0200
      Re: [patch] mm, vmscan: avoid thrashing anon lru when free + file is  low Minchan Kim <minchan@kernel.org> - 2017-04-19 02:20 +0200
        Re: [patch] mm, vmscan: avoid thrashing anon lru when free + file  is low David Rientjes <rientjes@google.com> - 2017-04-20 01:30 +0200
          Re: [patch] mm, vmscan: avoid thrashing anon lru when free + file is  low Minchan Kim <minchan@kernel.org> - 2017-04-20 08:10 +0200
      Re: [patch] mm, vmscan: avoid thrashing anon lru when free + file is  low Michal Hocko <mhocko@kernel.org> - 2017-04-19 09:10 +0200
  Re: [patch] mm, vmscan: avoid thrashing anon lru when free + file is  low Michal Hocko <mhocko@kernel.org> - 2017-04-18 09:20 +0200

csiph-web