Re: [PATCH v2] virtio: tx with can_push when VERSION_1 is set

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

On Wed, Nov 30, 2016 at 09:18:42AM +0000, Pierre Pfister (ppfister) wrote:
> Current virtio driver advertises VERSION_1 support,
> but does not handle device's VERSION_1 support when
> sending packets (it looks for ANY_LAYOUT feature,
> which is absent).
> 
> This patch enables 'can_push' in tx path when VERSION_1
> is advertised by the device.
> 
> This significantly improves small packets forwarding rate
> towards devices advertising VERSION_1 feature.
> 
> Signed-off-by: Pierre Pfister <ppfister@cisco.com>

>From the virtio spec point of view, that VERSION_1 implies ANY_LAYOUT,
this patch is right and I think we could apply this patch. No objections?

	--yliu
> ---
>  drivers/net/virtio/virtio_rxtx.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
> index 22d97a4..1e5a6b9 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -1015,7 +1015,8 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
>  		}
>  
>  		/* optimize ring usage */
> -		if (vtpci_with_feature(hw, VIRTIO_F_ANY_LAYOUT) &&
> +		if ((vtpci_with_feature(hw, VIRTIO_F_ANY_LAYOUT) ||
> +		      vtpci_with_feature(hw, VIRTIO_F_VERSION_1)) &&
>  		    rte_mbuf_refcnt_read(txm) == 1 &&
>  		    RTE_MBUF_DIRECT(txm) &&
>  		    txm->nb_segs == 1 &&
> -- 
> 2.7.4 (Apple Git-66)