From 931b92cc96a80c95fdf5762246926eaadee670a0 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 de4826a7cfe2984a8c3420d219973d2249baf9de (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 de4826a7cfe2984a8c3420d219973d2249baf9de). 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 656a02e28e266..a7e9ad9b213ae 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; -- 2.39.5