Explicit block device plugging when submitting multiple BIOs.

Without plugging, the default 'noop' scheduler will not merge the BIOs which are part of a large ZIO. Signed-off-by: Isaac Huang <[email protected]>
openzfs · Sep 27, 2016 · 0fa2c70 · 0fa2c70
1 parent 160987b
commit 0fa2c70
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/module/zfs/vdev_disk.c b/module/zfs/vdev_disk.c
@@ -524,6 +524,7 @@ __vdev_disk_physio(struct block_device *bdev, zio_t *zio, caddr_t kbuf_ptr,
 	uint64_t bio_offset;
 	int bio_size, bio_count = 16;
 	int i = 0, error = 0;
+	struct blk_plug plug;
 
 	ASSERT3U(kbuf_offset + kbuf_size, <=, bdev->bd_inode->i_size);
 
@@ -592,11 +593,17 @@ __vdev_disk_physio(struct block_device *bdev, zio_t *zio, caddr_t kbuf_ptr,
 	/* Extra reference to protect dio_request during vdev_submit_bio */
 	vdev_disk_dio_get(dr);
 
+	if (dr->dr_bio_count > 1)
+		blk_start_plug(&plug);
+
 	/* Submit all bio's associated with this dio */
 	for (i = 0; i < dr->dr_bio_count; i++)
 		if (dr->dr_bio[i])
 			vdev_submit_bio(dr->dr_bio[i]);
 
+	if (dr->dr_bio_count > 1)
+		blk_finish_plug(&plug);
+
 	(void) vdev_disk_dio_put(dr);
 
 	return (error);