virtio_balloon: introduce migration primitives to balloon pages

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, in order to
enhance the syncronization methods for accessing elements of struct
virtio_balloon, thus providing protection against concurrent access
introduced by parallel memory migration threads.

 - balloon_lock (mutex) : synchronizes the access demand to elements of
                          struct virtio_balloon and its queue operations;

[[email protected]: fix missing unlock on error in fill_balloon()]
[[email protected]: avoid having multiple return points in fill_balloon()]
[[email protected]: fix printk warning]Signed-off-by: Rafael Aquini <[email protected]>
Acked-by: Michael S. Tsirkin <[email protected]>
Cc: Rusty Russell <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Minchan Kim <[email protected]>
Signed-off-by: Wei Yongjun <[email protected]>

Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions