include/uapi/linux/virtio_blk.h: introduce feature of VIRTIO_BLK_F_MQ

Current virtio-blk spec only supports one virtual queue for transfering data between VM and host, and inside VM all kinds of operations on the virtual queue needs to hold one lock, so cause below problems: - bad scalability - bad throughput This patch requests to introduce feature of VIRTIO_BLK_F_MQ so that more than one virtual queues can be used to virtio-blk device, then above problems can be solved or eased. Signed-off-by: Ming Lei <[email protected]> Acked-by: Michael S. Tsirkin <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
torvalds · Jul 1, 2014 · cb55321 · cb55321
1 parent d151561
commit cb55321
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/include/uapi/linux/virtio_blk.h b/include/uapi/linux/virtio_blk.h
@@ -40,6 +40,7 @@
 #define VIRTIO_BLK_F_WCE	9	/* Writeback mode enabled after reset */
 #define VIRTIO_BLK_F_TOPOLOGY	10	/* Topology information is available */
 #define VIRTIO_BLK_F_CONFIG_WCE	11	/* Writeback mode available in config */
+#define VIRTIO_BLK_F_MQ		12	/* support more than one vq */
 
 #ifndef __KERNEL__
 /* Old (deprecated) name for VIRTIO_BLK_F_WCE. */
@@ -77,6 +78,10 @@ struct virtio_blk_config {
 
 	/* writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */
 	__u8 wce;
+	__u8 unused;
+
+	/* number of vqs, only available when VIRTIO_BLK_F_MQ is set */
+	__u16 num_queues;
 } __attribute__((packed));
 
 /*