From patchwork Mon Mar 6 04:15:34 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xuan Zhuo X-Patchwork-Id: 13160456 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 D2792C6FD1C for ; Mon, 6 Mar 2023 04:16:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229743AbjCFEQh (ORCPT ); Sun, 5 Mar 2023 23:16:37 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51088 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229665AbjCFEQe (ORCPT ); Sun, 5 Mar 2023 23:16:34 -0500 Received: from out30-101.freemail.mail.aliyun.com (out30-101.freemail.mail.aliyun.com [115.124.30.101]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 173FF1ABC2; Sun, 5 Mar 2023 20:16:06 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046056;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=13;SR=0;TI=SMTPD_---0Vd8Os24_1678076137; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0Vd8Os24_1678076137) by smtp.aliyun-inc.com; Mon, 06 Mar 2023 12:15:37 +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 Subject: [PATCH net 1/2] virtio_net: separate the logic of checking whether sq is full Date: Mon, 6 Mar 2023 12:15:34 +0800 Message-Id: <20230306041535.73319-2-xuanzhuo@linux.alibaba.com> X-Mailer: git-send-email 2.32.0.3.g01195cf9f In-Reply-To: <20230306041535.73319-1-xuanzhuo@linux.alibaba.com> References: <20230306041535.73319-1-xuanzhuo@linux.alibaba.com> MIME-Version: 1.0 X-Git-Hash: 340c28a36929 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 --- drivers/net/virtio_net.c | 59 ++++++++++++++++++++++++---------------- 1 file changed, 35 insertions(+), 24 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index fb5e68ed3ec2..777de0ec0b1b 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1750,6 +1750,40 @@ static void free_old_xmit_skbs(struct send_queue *sq, bool in_napi) u64_stats_update_end(&sq->stats.syncp); } +static void check_sq_full(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 bool is_xdp_raw_buffer_queue(struct virtnet_info *vi, int q) { if (q < (vi->curr_queue_pairs - vi->xdp_queue_pairs)) @@ -1989,30 +2023,7 @@ 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(vi, dev, sq); if (kick || netif_xmit_stopped(txq)) { if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {