| Message ID | 1440197635-5170-1-git-send-email-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 22/08/2015 00:53, Paolo Bonzini wrote: > 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> > --- > drivers/block/virtio_blk.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > index d4d05f064d39..ea2c17c66dfb 100644 > --- a/drivers/block/virtio_blk.c > +++ b/drivers/block/virtio_blk.c > @@ -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, > }; > > Ping? Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index d4d05f064d39..ea2c17c66dfb 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -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, };
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> --- drivers/block/virtio_blk.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)