Commit 0fbd050a authored Jul 31, 2015 by Eric Dumazet Committed by David S. Miller Aug 03, 2015

virtio_net: add gro capability



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@google.com>
Tested-by: Rick Jones <rick.jones2@hp.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 95b9be64

drivers/net/virtio_net.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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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