From: Mel Gorman <mgorman@suse.de>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
Linux-FSDevel <linux-fsdevel@vger.kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH 6/6] mm: page_alloc: Reduce cost of the fair zone allocation policy
Date: Mon, 11 Aug 2014 13:12:42 +0100 [thread overview]
Message-ID: <20140811121241.GD7970@suse.de> (raw)
In-Reply-To: <53E4EC53.1050904@suse.cz>
On Fri, Aug 08, 2014 at 05:27:15PM +0200, Vlastimil Babka wrote:
> On 07/09/2014 10:13 AM, Mel Gorman wrote:
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -1604,6 +1604,9 @@ again:
> > }
> >
> > __mod_zone_page_state(zone, NR_ALLOC_BATCH, -(1 << order));
>
> This can underflow zero, right?
>
Yes, because of per-cpu accounting drift.
> > + if (zone_page_state(zone, NR_ALLOC_BATCH) == 0 &&
>
> AFAICS, zone_page_state will correct negative values to zero only for
> CONFIG_SMP. Won't this check be broken on !CONFIG_SMP?
>
On !CONFIG_SMP how can there be per-cpu accounting drift that would make
that counter negative?
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2014-08-11 12:12 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-09 8:13 [PATCH 0/5] Reduce sequential read overhead Mel Gorman
2014-07-09 8:13 ` [PATCH 1/6] mm: pagemap: Avoid unnecessary overhead when tracepoints are deactivated Mel Gorman
2014-07-10 12:01 ` Johannes Weiner
2014-07-09 8:13 ` [PATCH 2/6] mm: Rearrange zone fields into read-only, page alloc, statistics and page reclaim lines Mel Gorman
2014-07-10 12:06 ` Johannes Weiner
2014-07-09 8:13 ` [PATCH 3/6] mm: Move zone->pages_scanned into a vmstat counter Mel Gorman
2014-07-10 12:08 ` Johannes Weiner
2014-07-09 8:13 ` [PATCH 4/6] mm: vmscan: Only update per-cpu thresholds for online CPU Mel Gorman
2014-07-10 12:09 ` Johannes Weiner
2014-07-09 8:13 ` [PATCH 5/6] mm: page_alloc: Abort fair zone allocation policy when remotes nodes are encountered Mel Gorman
2014-07-10 12:14 ` Johannes Weiner
2014-07-10 12:44 ` Mel Gorman
2014-07-09 8:13 ` [PATCH 6/6] mm: page_alloc: Reduce cost of the fair zone allocation policy Mel Gorman
2014-07-10 12:18 ` Johannes Weiner
2014-08-08 15:27 ` Vlastimil Babka
2014-08-11 12:12 ` Mel Gorman [this message]
2014-08-11 12:34 ` Vlastimil Babka
2014-09-02 14:01 ` Johannes Weiner
2014-09-05 10:14 ` [PATCH] mm: page_alloc: Fix setting of ZONE_FAIR_DEPLETED on UP Mel Gorman
2014-09-07 6:32 ` Leon Romanovsky
2014-09-08 11:57 ` [PATCH] mm: page_alloc: Fix setting of ZONE_FAIR_DEPLETED on UP v2 Mel Gorman
2014-09-09 19:53 ` Andrew Morton
2014-09-10 9:16 ` Mel Gorman
2014-09-10 20:32 ` Johannes Weiner
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