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Message-ID: <alpine.DEB.2.00.1107180951390.30392@router.home>
Date: Mon, 18 Jul 2011 09:56:31 -0500 (CDT)
From: Christoph Lameter <cl@...ux.com>
To: Mel Gorman <mgorman@...e.de>
cc: Andrew Morton <akpm@...ux-foundation.org>,
Minchan Kim <minchan.kim@...il.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] mm: page allocator: Initialise ZLC for first zone
eligible for zone_reclaim
On Fri, 15 Jul 2011, Mel Gorman wrote:
> Currently the zonelist cache is setup only after the first zone has
> been considered and zone_reclaim() has been called. The objective was
> to avoid a costly setup but zone_reclaim is itself quite expensive. If
> it is failing regularly such as the first eligible zone having mostly
> mapped pages, the cost in scanning and allocation stalls is far higher
> than the ZLC initialisation step.
Would it not be easier to set zlc_active and allowednodes based on the
zone having an active ZLC at the start of get_pages()?
Buffered_rmqueue is handling the situation of a zone with an ZLC in a
weird way right now since it ignores the (potentially existing) ZLC
for the first pass. zlc_setup() does a lot of things. So that is because
there is a performance benefit?
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