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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: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Paolo Bonzini 2015-08-21 15:53:55 -07:00 committed by Michael S. Tsirkin
parent 64291f7db5
commit 53eab6fd27
1 changed files with 2 additions and 3 deletions
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5
drivers/block/virtio_blk.c
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@ -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,
};