From ba275241030cfe87b87d6592345c7e7ebd9b6fba Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Fri, 1 Nov 2013 14:07:48 +0800 Subject: [PATCH] virtio-net: coalesce rx frags when possible during rx 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 before 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 Cc: Michael S. Tsirkin Cc: Michael Dalton Cc: Eric Dumazet Acked-by: Michael S. Tsirkin Acked-by: Eric Dumazet Signed-off-by: Jason Wang Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- drivers/net/virtio_net.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 656a02e..a7e9ad9 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 +342,16 @@ 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)) { + put_page(page); + 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; -- 2.7.4