On Thu, Jan 31, 2019 at 08:40:30PM +0900, Toshiaki Makita wrote:
> Previously virtnet_xdp_xmit() did not account for device tx counters,
> which caused confusions.
> To be consistent with SKBs, account them on freeing xdp_frames.
>
> Reported-by: David Ahern <dsahern@xxxxxxxxx>
> Signed-off-by: Toshiaki Makita <makita.toshiaki@xxxxxxxxxxxxx>
Well we count them on receive so I guess it makes sense for consistency
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
however, I really wonder whether adding more and more standard net stack
things like this will end up costing most of XDP its speed.
Should we instead make sure *not* to account XDP packets
in any counters at all? XDP programs can use maps
to do their own counting...
> ---
> drivers/net/virtio_net.c | 20 ++++++++++++++++----
> 1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 2594481..4cfceb7 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -503,6 +503,8 @@ static int virtnet_xdp_xmit(struct net_device *dev,
> struct bpf_prog *xdp_prog;
> struct send_queue *sq;
> unsigned int len;
> + int packets = 0;
> + int bytes = 0;
> int drops = 0;
> int kicks = 0;
> int ret, err;
> @@ -526,10 +528,18 @@ static int virtnet_xdp_xmit(struct net_device *dev,
>
> /* Free up any pending old buffers before queueing new ones. */
> while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
> - if (likely(is_xdp_frame(ptr)))
> - xdp_return_frame(ptr_to_xdp(ptr));
> - else
> - napi_consume_skb(ptr, false);
> + if (likely(is_xdp_frame(ptr))) {
> + struct xdp_frame *frame = ptr_to_xdp(ptr);
> +
> + bytes += frame->len;
> + xdp_return_frame(frame);
> + } else {
> + struct sk_buff *skb = ptr;
> +
> + bytes += skb->len;
> + napi_consume_skb(skb, false);
> + }
> + packets++;
> }
>
> for (i = 0; i < n; i++) {
> @@ -549,6 +559,8 @@ static int virtnet_xdp_xmit(struct net_device *dev,
> }
> out:
> u64_stats_update_begin(&sq->stats.syncp);
> + sq->stats.bytes += bytes;
> + sq->stats.packets += packets;
> sq->stats.xdp_tx += n;
> sq->stats.xdp_tx_drops += drops;
> sq->stats.kicks += kicks;
> --
> 1.8.3.1
>
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