Re: [PATCH net-next] virtio_net: add gro capability
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2015-08-03 13:37:19
Also in:
virtualization
On Fri, Jul 31, 2015 at 06:25:17PM +0200, Eric Dumazet wrote:
From: Eric Dumazet <edumazet@google.com>
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 <redacted>
Cc: "Michael S. Tsirkin" <mst@redhat.com>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@redhat.com>
quoted hunk ↗ jump to hunk
--- 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);