block: add queue flag for paravirt frontend drivers

As is the case with SSD devices, we do not want to idle in AS/CFQ when the block device is a paravirt front-end driver. This patch adds a flag (QUEUE_FLAG_VIRT) which should be used by front-end drivers such as virtio_blk and xen-blkfront to indicate a paravirtualized device. Signed-off-by: Fernando Luis Vazquez Cao <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
vbatts · Dec 29, 2008 · 88e740f · 88e740f
1 parent 3c92ec8
commit 88e740f
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
@@ -449,6 +449,7 @@ struct request_queue
 #define QUEUE_FLAG_FAIL_IO     12	/* fake timeout */
 #define QUEUE_FLAG_STACKABLE   13	/* supports request stacking */
 #define QUEUE_FLAG_NONROT      14	/* non-rotational device (SSD) */
+#define QUEUE_FLAG_VIRT        QUEUE_FLAG_NONROT /* paravirt device */
 
 static inline int queue_is_locked(struct request_queue *q)
 {