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Commit 53eab6fd authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Michael S. Tsirkin
Browse files

virtio-blk: use VIRTIO_BLK_F_WCE and VIRTIO_BLK_F_CONFIG_WCE in virtio1 



VIRTIO_BLK_F_CONFIG_WCE is important in order to achieve good performance
(up to 2x, though more realistically +30-40%) in latency-bound workloads.
However, it was removed by mistake together with VIRTIO_BLK_F_FLUSH.

It will be restored in the next revision of the virtio 1.0 standard, so
do the same in Linux.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 64291f7d

drivers/block/virtio_blk.c

+2 −3
Original line number Diff line number Diff line
@@ -478,8 +478,7 @@ static int virtblk_get_cache_mode(struct virtio_device *vdev) 
				   struct virtio_blk_config, wce,

				   &writeback);

	if (err)

		writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE) ||

		            virtio_has_feature(vdev, VIRTIO_F_VERSION_1);

		writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE);



	return writeback;

}
@@ -840,7 +839,7 @@ static unsigned int features_legacy[] = { 
static unsigned int features[] = {

	VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,

	VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,

	VIRTIO_BLK_F_TOPOLOGY,

	VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,

	VIRTIO_BLK_F_MQ,

};