linux-kernel - Re: [PATCH 4/7] Memory compaction core

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Date:	Wed, 06 Jan 2010 22:37:22 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Mel Gorman <mel@....ul.ie>
Cc:	Andrea Arcangeli <aarcange@...hat.com>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Adam Litke <agl@...ibm.com>, Avi Kivity <avi@...hat.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 4/7] Memory compaction core

Mel Gorman <mel@....ul.ie> writes:


Haven't reviewed the full thing, but one thing I noticed below:

> +
> +	/*
> +	 * Isolate free pages until enough are available to migrate the
> +	 * pages on cc->migratepages. We stop searching if the migrate
> +	 * and free page scanners meet or enough free pages are isolated.
> +	 */
> +	spin_lock_irq(&zone->lock);

Won't that cause very long lock hold times on large zones?
Presumably you need some kind of lock break heuristic.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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