From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH net-next 2/2] virtio-net: coalesce rx frags when possible during rx Date: Thu, 31 Oct 2013 13:41:53 +0200 Message-ID: <20131031114153.GD8976@redhat.com> References: <1383215313-23651-1-git-send-email-jasowang@redhat.com> <1383215313-23651-2-git-send-email-jasowang@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: mwdalton@google.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, edumazet@google.com, davem@davemloft.net To: Jason Wang Return-path: Content-Disposition: inline In-Reply-To: <1383215313-23651-2-git-send-email-jasowang@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org On Thu, Oct 31, 2013 at 06:28:33PM +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 > Cc: Michael S. Tsirkin > Cc: Michael Dalton > Cc: Eric Dumazet > Signed-off-by: Jason Wang Good idea. Acked-by: Michael S. Tsirkin > --- > 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