[PATCH v2 repost 2/7] virtio-balloon: define new feature bit and page bitmap head

Liang Li
2016-07-27T01:23:31Z

Add a new feature which supports sending the page information with
a bitmap. The current implementation uses PFNs array, which is not
very efficient. Using bitmap can improve the performance of
inflating/deflating significantly

The page bitmap header will used to tell the host some information
about the page bitmap. e.g. the page size, page bitmap length and
start pfn.

Signed-off-by: Liang Li <liang.z.li@intel.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Amit Shah <amit.shah@redhat.com>
---
include/uapi/linux/virtio_balloon.h | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
index 343d7dd..d3b182a 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -34,6 +34,7 @@
#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */
+#define VIRTIO_BALLOON_F_PAGE_BITMAP 3 /* Send page info with bitmap */

/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
@@ -82,4 +83,22 @@ struct virtio_balloon_stat {
__virtio64 val;
} __attribute__((packed));

+/* Page bitmap header structure */
+struct balloon_bmap_hdr {
+ /* Used to distinguish different request */
+ __virtio16 cmd;
+ /* Shift width of page in the bitmap */
+ __virtio16 page_shift;
+ /* flag used to identify different status */
+ __virtio16 flag;
+ /* Reserved */
+ __virtio16 reserved;
+ /* ID of the request */
+ __virtio64 req_id;
+ /* The pfn of 0 bit in the bitmap */
+ __virtio64 start_pfn;
+ /* The length of the bitmap, in bytes */
+ __virtio64 bmap_len;
+};
+
#endif /* _LINUX_VIRTIO_BALLOON_H */
--
1.9.1