From patchwork Wed Apr 7 05:49:49 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xuan Zhuo X-Patchwork-Id: 12186947 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C322AC433ED for ; Wed, 7 Apr 2021 05:49:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9C801613C2 for ; Wed, 7 Apr 2021 05:49:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244364AbhDGFuC (ORCPT ); Wed, 7 Apr 2021 01:50:02 -0400 Received: from out30-56.freemail.mail.aliyun.com ([115.124.30.56]:57647 "EHLO out30-56.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229558AbhDGFuB (ORCPT ); Wed, 7 Apr 2021 01:50:01 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R971e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0UUlTeLB_1617774589; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0UUlTeLB_1617774589) by smtp.aliyun-inc.com(127.0.0.1); Wed, 07 Apr 2021 13:49:49 +0800 From: Xuan Zhuo To: Jason Wang Cc: "Michael S. Tsirkin" , "David S. Miller" , Jakub Kicinski , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH net-next] virtio-net: page_to_skb() use build_skb when there's sufficient tailroom Date: Wed, 7 Apr 2021 13:49:49 +0800 Message-Id: <20210407054949.98211-1-xuanzhuo@linux.alibaba.com> X-Mailer: git-send-email 2.31.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org In page_to_skb(), if we have enough tailroom to save skb_shared_info, we can use build_skb to create skb directly. No need to alloc for additional space. And it can save a 'frags slot', which is very friendly to GRO. Here, if the payload of the received package is too small (less than GOOD_COPY_LEN), we still choose to copy it directly to the space got by napi_alloc_skb. So we can reuse these pages. Testing Machine: The four queues of the network card are bound to the cpu1. Test command: for ((i=0;i<5;++i)); do sockperf tp --ip 192.168.122.64 -m 1000 -t 150& done The size of the udp package is 1000, so in the case of this patch, there will always be enough tailroom to use build_skb. The sent udp packet will be discarded because there is no port to receive it. The irqsoftd of the machine is 100%, we observe the received quantity displayed by sar -n DEV 1: no build_skb: 956864.00 rxpck/s build_skb: 1158465.00 rxpck/s Signed-off-by: Xuan Zhuo Suggested-by: Jason Wang --- drivers/net/virtio_net.c | 51 ++++++++++++++++++++++++++-------------- 1 file changed, 33 insertions(+), 18 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index bb4ea9dbc16b..5071a8a8f57a 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -383,17 +383,11 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, { struct sk_buff *skb; struct virtio_net_hdr_mrg_rxbuf *hdr; - unsigned int copy, hdr_len, hdr_padded_len; - char *p; + unsigned int copy, hdr_len, hdr_padded_len, tailroom, shinfo_size; + char *p, *hdr_p; p = page_address(page) + offset; - - /* copy small packet so we can reuse these pages for small data */ - skb = napi_alloc_skb(&rq->napi, GOOD_COPY_LEN); - if (unlikely(!skb)) - return NULL; - - hdr = skb_vnet_hdr(skb); + hdr_p = p; hdr_len = vi->hdr_len; if (vi->mergeable_rx_bufs) @@ -401,24 +395,33 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, else hdr_padded_len = sizeof(struct padded_vnet_hdr); - /* hdr_valid means no XDP, so we can copy the vnet header */ - if (hdr_valid) - memcpy(hdr, p, hdr_len); + tailroom = truesize - len; len -= hdr_len; offset += hdr_padded_len; p += hdr_padded_len; + shinfo_size = SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); + + if (len > GOOD_COPY_LEN && tailroom >= shinfo_size) { + skb = build_skb(p, truesize); + if (unlikely(!skb)) + return NULL; + + skb_put(skb, len); + goto ok; + } + + /* copy small packet so we can reuse these pages for small data */ + skb = napi_alloc_skb(&rq->napi, GOOD_COPY_LEN); + if (unlikely(!skb)) + return NULL; + copy = len; if (copy > skb_tailroom(skb)) copy = skb_tailroom(skb); skb_put_data(skb, p, copy); - if (metasize) { - __skb_pull(skb, metasize); - skb_metadata_set(skb, metasize); - } - len -= copy; offset += copy; @@ -427,7 +430,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, skb_add_rx_frag(skb, 0, page, offset, len, truesize); else put_page(page); - return skb; + goto ok; } /* @@ -454,6 +457,18 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, if (page) give_pages(rq, page); +ok: + /* hdr_valid means no XDP, so we can copy the vnet header */ + if (hdr_valid) { + hdr = skb_vnet_hdr(skb); + memcpy(hdr, hdr_p, hdr_len); + } + + if (metasize) { + __skb_pull(skb, metasize); + skb_metadata_set(skb, metasize); + } + return skb; }