From: Mel Gorman <mgorman@suse.de>
To: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
akpm@linux-foundation.org, Josh Boyer <jwboyer@redhat.com>,
aarcange@redhat.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] mm: Abort reclaim/compaction if compaction can proceed
Date: Fri, 7 Oct 2011 21:24:17 +0100 [thread overview]
Message-ID: <20111007202417.GD6418@suse.de> (raw)
In-Reply-To: <4E8F5BEA.3040502@redhat.com>
On Fri, Oct 07, 2011 at 04:07:06PM -0400, Rik van Riel wrote:
> On 10/07/2011 11:17 AM, Mel Gorman wrote:
> >If compaction can proceed, shrink_zones() stops doing any work but
> >the callers still shrink_slab(), raises the priority and potentially
> >sleeps. This patch aborts direct reclaim/compaction entirely if
> >compaction can proceed.
> >
> >Signed-off-by: Mel Gorman<mgorman@suse.de>
>
> This patch makes sense to me, but I have not tested it like
> the first one.
>
Do if you can.
> Mel, have you tested this patch?
Yes.
> Did you see any changed
> behaviour vs. just the first patch?
>
It's marginal and could be confirmation bias on my part. Basically,
there is noise when this path is being exercised but there were fewer
slabs scanned. However, I don't know what the variances are and
whether the reduction was within the noise or not but it makes sense
that it would scan less. If I profiled carefully, I might be able
to show that a few additional cycles are spent raising the priority
but it would be marginal.
While patch 1 is very clear, patch 2 depends on reviewers deciding it
"makes sense".
> Having said that, I'm pretty sure the patch is ok :)
>
Care to ack?
--
Mel Gorman
SUSE Labs
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next prev parent reply other threads:[~2011-10-07 20:24 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-07 15:17 [PATCH 0/2] Avoid excessive reclaim due to THP Mel Gorman
2011-10-07 15:17 ` [PATCH 1/2] mm: vmscan: Limit direct reclaim for higher order allocations Mel Gorman
2011-10-07 19:32 ` Rik van Riel
2011-10-07 20:18 ` Mel Gorman
2011-10-09 8:02 ` Minchan Kim
2011-10-07 15:17 ` [PATCH 2/2] mm: Abort reclaim/compaction if compaction can proceed Mel Gorman
2011-10-07 20:07 ` Rik van Riel
2011-10-07 20:24 ` Mel Gorman [this message]
2011-10-07 22:42 ` Rik van Riel
2011-10-09 8:04 ` Minchan Kim
2011-10-12 14:57 ` Johannes Weiner
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