linux-kernel - Re: [PATCH v6 2/3] virtio_balloon: introduce migration primitives to balloon pages

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Message-ID: <502314C3.2020509@redhat.com>
Date:	Wed, 08 Aug 2012 21:39:15 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Rafael Aquini <aquini@...hat.com>
CC:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org,
	Rusty Russell <rusty@...tcorp.com.au>,
	"Michael S. Tsirkin" <mst@...hat.com>, Mel Gorman <mel@....ul.ie>,
	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Minchan Kim <minchan@...nel.org>
Subject: Re: [PATCH v6 2/3] virtio_balloon: introduce migration primitives
 to balloon pages

On 08/08/2012 06:53 PM, Rafael Aquini wrote:
> Memory fragmentation introduced by ballooning might reduce significantly
> the number of 2MB contiguous memory blocks that can be used within a guest,
> thus imposing performance penalties associated with the reduced number of
> transparent huge pages that could be used by the guest workload.
>
> Besides making balloon pages movable at allocation time and introducing
> the necessary primitives to perform balloon page migration/compaction,
> this patch also introduces the following locking scheme to provide the
> proper synchronization and protection for struct virtio_balloon elements
> against concurrent accesses due to parallel operations introduced by
> memory compaction / page migration.
>   - balloon_lock (mutex) : synchronizes the access demand to elements of
> 			  struct virtio_balloon and its queue operations;
>   - pages_lock (spinlock): special protection to balloon pages list against
> 			  concurrent list handling operations;
>
> Signed-off-by: Rafael Aquini<aquini@...hat.com>

Reviewed-by: Rik van Riel <riel@...hat.com>

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