Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753928Ab3JaK26 (ORCPT ); Thu, 31 Oct 2013 06:28:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51127 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752459Ab3JaK24 (ORCPT ); Thu, 31 Oct 2013 06:28:56 -0400 From: Jason Wang To: davem@davemloft.net, edumazet@google.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, mst@redhat.com, rusty@rustcorp.com.au, mwdalton@google.com, virtualization@lists.linux-foundation.org Cc: Jason Wang Subject: [PATCH net-next 2/2] virtio-net: coalesce rx frags when possible during rx Date: Thu, 31 Oct 2013 18:28:33 +0800 Message-Id: <1383215313-23651-2-git-send-email-jasowang@redhat.com> In-Reply-To: <1383215313-23651-1-git-send-email-jasowang@redhat.com> References: <1383215313-23651-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2846 Lines: 78 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 Cc: Michael S. Tsirkin Cc: Michael Dalton Cc: Eric Dumazet Signed-off-by: Jason Wang --- drivers/net/virtio_net.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 113ee93..4ff4f78 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, + offset, len, MAX_PACKET_LEN); + } else { + skb_add_rx_frag(curr_skb, num_skb_frags, page, + offset, len, + MAX_PACKET_LEN); + } --rq->num; } return 0; -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/