On Thu, Jun 07, 2018 at 04:38:26PM +0200, Maxime Coquelin wrote:
> vhost_vring_call() used rte_mb(), which translates into
> mfence instruction on x86.
>
> This patch changes to use rte_smp_mb(), which changed recently
> to translate into a locked ADD instruction for performance
> reason.
>
> The measured gain is up to 3% with the testpmd benchmarks.
>
> Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
> ---
> lib/librte_vhost/vhost.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 58c425a5c..1bc99ed3c 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -591,7 +591,7 @@ static __rte_always_inline void
> vhost_vring_call(struct virtio_net *dev, struct vhost_virtqueue *vq)
> {
> /* Flush used->idx update before we read avail->flags. */
> - rte_mb();
> + rte_smp_mb();
>
> /* Don't kick guest if we don't reach index specified by guest. */
> if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX)) {
> --
> 2.14.3
>
Reviewed-by: Tiwei Bie <tiwei....@intel.com>
