| Message ID | 1383220027-12278-2-git-send-email-jasowang@redhat.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu, 2013-10-31 at 19:47 +0800, Jason Wang wrote: > Commit 2613af0ed18a11d5c566a81f9a6510b73180660a (virtio_net: migrate mergeable > rx buffers to page frag allocators) try to increase the payload/truesize for > MTU-sized traffic. But this will introduce the extra overhead for GSO packets > received because of the frag list. This commit tries to reduce this issue by > coalesce the possible rx frags when possible during rx. Test result shows the > about 15% improvement on full size GSO packet receiving (and even better than > commit 2613af0ed18a11d5c566a81f9a6510b73180660a). > > Before this commit: > ./netperf -H 192.168.100.4 > MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.100.4 > () port 0 AF_INET : demo > Recv Send Send > Socket Socket Message Elapsed > Size Size Size Time Throughput > bytes bytes bytes secs. 10^6bits/sec > > 87380 16384 16384 10.00 20303.87 > > After this commit: > ./netperf -H 192.168.100.4 > MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.100.4 () port 0 AF_INET : demo > Recv Send Send > Socket Socket Message Elapsed > Size Size Size Time Throughput > bytes bytes bytes secs. 10^6bits/sec > > 87380 16384 16384 10.00 23841.26 > > Cc: Rusty Russell <rusty@rustcorp.com.au> > Cc: Michael S. Tsirkin <mst@redhat.com> > Cc: Michael Dalton <mwdalton@google.com> > Cc: Eric Dumazet <edumazet@google.com> > Acked-by: Michael S. Tsirkin <mst@redhat.com> > Signed-off-by: Jason Wang <jasowang@redhat.com> > --- Excellent ! We now have 2 or 3 frags per skb, like tcp stack manages to do on output path. Michael Dalton is also working on a autotuning patch, using an EWMA, so that the size of individual sg blocks can vary from 1500 to 4096, this might show even better throughput, we'll see. Acked-by: Eric Dumazet <edumazet@google.com> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 113ee93..5dc0de0 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -305,7 +305,7 @@ static int receive_mergeable(struct receive_queue *rq, struct sk_buff *head_skb) struct sk_buff *curr_skb = head_skb; char *buf; struct page *page; - int num_buf, len; + int num_buf, len, offset; num_buf = hdr->mhdr.num_buffers; while (--num_buf) { @@ -342,9 +342,15 @@ static int receive_mergeable(struct receive_queue *rq, struct sk_buff *head_skb) head_skb->truesize += MAX_PACKET_LEN; } page = virt_to_head_page(buf); - skb_add_rx_frag(curr_skb, num_skb_frags, page, - buf - (char *)page_address(page), len, - MAX_PACKET_LEN); + offset = buf - (char *)page_address(page); + if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) { + skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1, + len, MAX_PACKET_LEN); + } else { + skb_add_rx_frag(curr_skb, num_skb_frags, page, + offset, len, + MAX_PACKET_LEN); + } --rq->num; } return 0;