From patchwork Wed Mar 8 02:49:34 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xuan Zhuo X-Patchwork-Id: 13165147 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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C4891C6FD20 for ; Wed, 8 Mar 2023 02:49:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229760AbjCHCto (ORCPT ); Tue, 7 Mar 2023 21:49:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229716AbjCHCtn (ORCPT ); Tue, 7 Mar 2023 21:49:43 -0500 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BCA5D9273F; Tue, 7 Mar 2023 18:49:41 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R811e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045168;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=15;SR=0;TI=SMTPD_---0VdNGxDg_1678243777; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0VdNGxDg_1678243777) by smtp.aliyun-inc.com; Wed, 08 Mar 2023 10:49:37 +0800 From: Xuan Zhuo To: netdev@vger.kernel.org Cc: "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , virtualization@lists.linux-foundation.org, bpf@vger.kernel.org, Yichun Zhang , Alexander Duyck Subject: [PATCH net, stable v1 2/3] virtio_net: separate the logic of checking whether sq is full Date: Wed, 8 Mar 2023 10:49:34 +0800 Message-Id: <20230308024935.91686-3-xuanzhuo@linux.alibaba.com> X-Mailer: git-send-email 2.32.0.3.g01195cf9f In-Reply-To: <20230308024935.91686-1-xuanzhuo@linux.alibaba.com> References: <20230308024935.91686-1-xuanzhuo@linux.alibaba.com> MIME-Version: 1.0 X-Git-Hash: 8a00faae1554 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Separate the logic of checking whether sq is full. The subsequent patch will reuse this func. Signed-off-by: Xuan Zhuo Reviewed-by: Alexander Duyck Acked-by: Michael S. Tsirkin Acked-by: Jason Wang --- drivers/net/virtio_net.c | 60 ++++++++++++++++++++++++---------------- 1 file changed, 36 insertions(+), 24 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 8b31a04052f2..46bbddaadb0d 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -591,6 +591,41 @@ static bool is_xdp_raw_buffer_queue(struct virtnet_info *vi, int q) return false; } +static void check_sq_full_and_disable(struct virtnet_info *vi, + struct net_device *dev, + struct send_queue *sq) +{ + bool use_napi = sq->napi.weight; + int qnum; + + qnum = sq - vi->sq; + + /* If running out of space, stop queue to avoid getting packets that we + * are then unable to transmit. + * An alternative would be to force queuing layer to requeue the skb by + * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be + * returned in a normal path of operation: it means that driver is not + * maintaining the TX queue stop/start state properly, and causes + * the stack to do a non-trivial amount of useless work. + * Since most packets only take 1 or 2 ring slots, stopping the queue + * early means 16 slots are typically wasted. + */ + if (sq->vq->num_free < 2+MAX_SKB_FRAGS) { + netif_stop_subqueue(dev, qnum); + if (use_napi) { + if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) + virtqueue_napi_schedule(&sq->napi, sq->vq); + } else if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) { + /* More just got used, free them then recheck. */ + free_old_xmit_skbs(sq, false); + if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) { + netif_start_subqueue(dev, qnum); + virtqueue_disable_cb(sq->vq); + } + } + } +} + static int __virtnet_xdp_xmit_one(struct virtnet_info *vi, struct send_queue *sq, struct xdp_frame *xdpf) @@ -1989,30 +2024,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) nf_reset_ct(skb); } - /* If running out of space, stop queue to avoid getting packets that we - * are then unable to transmit. - * An alternative would be to force queuing layer to requeue the skb by - * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be - * returned in a normal path of operation: it means that driver is not - * maintaining the TX queue stop/start state properly, and causes - * the stack to do a non-trivial amount of useless work. - * Since most packets only take 1 or 2 ring slots, stopping the queue - * early means 16 slots are typically wasted. - */ - if (sq->vq->num_free < 2+MAX_SKB_FRAGS) { - netif_stop_subqueue(dev, qnum); - if (use_napi) { - if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) - virtqueue_napi_schedule(&sq->napi, sq->vq); - } else if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) { - /* More just got used, free them then recheck. */ - free_old_xmit_skbs(sq, false); - if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) { - netif_start_subqueue(dev, qnum); - virtqueue_disable_cb(sq->vq); - } - } - } + check_sq_full_and_disable(vi, dev, sq); if (kick || netif_xmit_stopped(txq)) { if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {