From: Andrea Arcangeli <aarcange@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Shaohua Li <shli@kernel.org>, linux-mm@kvack.org, mgorman@suse.de
Subject: Re: [patch 1/2 v2]compaction: abort compaction loop if lock is contended or run too long
Date: Thu, 13 Sep 2012 01:48:08 +0200 [thread overview]
Message-ID: <20120912234808.GC3404@redhat.com> (raw)
In-Reply-To: <20120912142019.0e06bf52.akpm@linux-foundation.org>
On Wed, Sep 12, 2012 at 02:20:19PM -0700, Andrew Morton wrote:
> OK, I'll slip this in there:
>
> --- a/mm/compaction.c~mm-compaction-abort-compaction-loop-if-lock-is-contended-or-run-too-long-fix
> +++ a/mm/compaction.c
> @@ -909,8 +909,7 @@ static unsigned long compact_zone_order(
> INIT_LIST_HEAD(&cc.migratepages);
>
> ret = compact_zone(zone, &cc);
> - if (contended)
> - *contended = cc.contended;
> + *contended = cc.contended;
> return ret;
> }
Ack the above, thanks.
One more thing, today a bug tripped while building cyanogenmod10 (it
swaps despite so much ram) after I added the cc->contended loop break
patch. The original version of the fix from Shaohua didn't have this
problem because it would only abort compaction if the low_pfn didn't
advance and in turn the list would be guaranteed empty.
Verifying the list is empty before aborting compaction (which takes a
path that ignores the cc->migratelist) should be enough to fix it and
it makes it really equivalent to the previous fix. Both cachelines
should be cache hot so it should be practically zero cost to check it.
Only lightly tested so far.
===
next prev parent reply other threads:[~2012-09-12 23:48 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-10 1:18 [patch 1/2 v2]compaction: abort compaction loop if lock is contended or run too long Shaohua Li
2012-09-10 8:11 ` Mel Gorman
2012-09-11 1:45 ` Minchan Kim
2012-09-11 8:29 ` Shaohua Li
2012-09-11 8:40 ` Minchan Kim
2012-09-11 23:34 ` Andrew Morton
2012-09-12 0:48 ` Andrea Arcangeli
2012-09-12 21:20 ` Andrew Morton
2012-09-12 23:48 ` Andrea Arcangeli [this message]
2012-09-13 0:47 ` Minchan Kim
2012-09-13 2:49 ` Shaohua Li
2012-09-13 9:38 ` Mel Gorman
2012-09-13 10:13 ` Shaohua Li
2012-09-13 16:04 ` Andrea Arcangeli
2012-09-13 16:31 ` Mel Gorman
2012-09-13 17:11 ` Andrea Arcangeli
2012-09-13 10:03 ` Mel Gorman
2012-09-12 11:08 ` Mel Gorman
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