Commit e407f39a authored Oct 27, 2015 by Michael S. Tsirkin Committed by David S. Miller Oct 27, 2015

vhost: fix performance on LE hosts



commit 2751c988 ("vhost: cross-endian
support for legacy devices") introduced a minor regression: even with
cross-endian disabled, and even on LE host, vhost_is_little_endian is
checking is_le flag so there's always a branch.

To fix, simply check virtio_legacy_is_little_endian first.

Cc: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 85ff8a43

drivers/vhost/vhost.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -183,10 +183,17 @@ static inline bool vhost_has_feature(struct vhost_virtqueue *vq, int bit)
		return vq->acked_features & (1ULL << bit);
		}

		#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
		static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq)
		{
		return vq->is_le;
		}
		#else
		static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq)
		{
		return virtio_legacy_is_little_endian() \|\| vq->is_le;
		}
		#endif

		/* Memory accessors */
		static inline u16 vhost16_to_cpu(struct vhost_virtqueue *vq, __virtio16 val)

Admin message