On Fri, Jul 31, 2015 at 06:25:17PM +0200, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@xxxxxxxxxx>
>
> Straightforward patch to add GRO processing to virtio_net.
>
> napi_complete_done() usage allows more aggressive aggregation,
> opted-in by setting /sys/class/net/xxx/gro_flush_timeout
>
> Tested:
>
> Setting /sys/class/net/xxx/gro_flush_timeout to 1000 nsec,
> Rick Jones reported following results.
>
> One VM of each on a pair of OpenStack compute nodes with E5-2650Lv3 CPUs
> and Intel 82599ES-based NICs. So, two "before" and two "after" VMs.
> The OpenStack compute nodes were running OpenStack Kilo, with VxLAN
> encapsulation being used through OVS so no GRO coming-up the host
> stack. The compute nodes themselves were running a 3.14-based kernel.
>
> Single-stream netperf, CPU utilizations and thus service demands are
> based on intra-guest reported CPU.
>
> Throughput Mbit/s, bigger is better
> Min Median Average Max
> 4.2.0-rc3+ 1364 1686 1678 1938
> 4.2.0-rc3+flush1k 1824 2269 2275 2647
>
> Send Service Demand, smaller is better
> Min Median Average Max
> 4.2.0-rc3+ 0.236 0.558 0.524 0.802
> 4.2.0-rc3+flush1k 0.176 0.503 0.471 0.738
>
> Receive Service Demand, smaller is better.
> Min Median Average Max
> 4.2.0-rc3+ 1.906 2.188 2.191 2.531
> 4.2.0-rc3+flush1k 0.448 0.529 0.533 0.692
>
>
> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> Tested-by: Rick Jones <rick.jones2@xxxxxx>
> Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Ideally this needs to also be tested on non-vxlan configs with gro in
host, to make sure this doesn't cause regressions.
But I don't see why it should: GRO overhead is pretty small if packets
don't need to be combined.
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
> drivers/net/virtio_net.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7fbca37a1adf..66f08f622dc6 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -518,7 +518,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
>
> skb_mark_napi_id(skb, &rq->napi);
>
> - netif_receive_skb(skb);
> + napi_gro_receive(&rq->napi, skb);
> return;
>
> frame_err:
> @@ -756,7 +756,7 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
> /* Out of packets? */
> if (received < budget) {
> r = virtqueue_enable_cb_prepare(rq->vq);
> - napi_complete(napi);
> + napi_complete_done(napi, received);
> if (unlikely(virtqueue_poll(rq->vq, r)) &&
> napi_schedule_prep(napi)) {
> virtqueue_disable_cb(rq->vq);
>
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