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

[Rik van Riel <riel@redhat.com>]

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@redhat.com>

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

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