From patchwork Wed Dec 20 08:07:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Heng Qi X-Patchwork-Id: 13499643 X-Patchwork-Delegate: kuba@kernel.org Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2F82F1799D for ; Wed, 20 Dec 2023 08:07:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046051;MF=hengqi@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0Vytfnwx_1703059647; Received: from localhost(mailfrom:hengqi@linux.alibaba.com fp:SMTPD_---0Vytfnwx_1703059647) by smtp.aliyun-inc.com; Wed, 20 Dec 2023 16:07:28 +0800 From: Heng Qi To: netdev@vger.kernel.org, virtualization@lists.linux-foundation.org Cc: Jason Wang , "Michael S. Tsirkin" , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Xuan Zhuo Subject: [PATCH net-next] virtio-net: switch napi_tx without downing nic Date: Wed, 20 Dec 2023 16:07:27 +0800 Message-Id: X-Mailer: git-send-email 2.19.1.6.gb485710b Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org virtio-net has two ways to switch napi_tx: one is through the module parameter, and the other is through coalescing parameter settings (provided that the nic status is down). Sometimes we face performance regression caused by napi_tx, then we need to switch napi_tx when debugging. However, the existing methods are a bit troublesome, such as needing to reload the driver or turn off the network card. So try to make this update. Signed-off-by: Heng Qi Reviewed-by: Xuan Zhuo --- drivers/net/virtio_net.c | 81 ++++++++++++++++++---------------------- 1 file changed, 37 insertions(+), 44 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 10614e9f7cad..12f8e1f9971c 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -3559,16 +3559,37 @@ static int virtnet_coal_params_supported(struct ethtool_coalesce *ec) return 0; } -static int virtnet_should_update_vq_weight(int dev_flags, int weight, - int vq_weight, bool *should_update) +static void virtnet_switch_napi_tx(struct virtnet_info *vi, u32 qstart, + u32 qend, u32 tx_frames) { - if (weight ^ vq_weight) { - if (dev_flags & IFF_UP) - return -EBUSY; - *should_update = true; - } + struct net_device *dev = vi->dev; + int new_weight, cur_weight; + struct netdev_queue *txq; + struct send_queue *sq; - return 0; + new_weight = tx_frames ? NAPI_POLL_WEIGHT : 0; + for (; qstart < qend; qstart++) { + sq = &vi->sq[qstart]; + cur_weight = sq->napi.weight; + if (!(new_weight ^ cur_weight)) + continue; + + if (!(dev->flags & IFF_UP)) { + sq->napi.weight = new_weight; + continue; + } + + if (cur_weight) + virtnet_napi_tx_disable(&sq->napi); + + txq = netdev_get_tx_queue(dev, qstart); + __netif_tx_lock_bh(txq); + sq->napi.weight = new_weight; + __netif_tx_unlock_bh(txq); + + if (!cur_weight) + virtnet_napi_tx_enable(vi, sq->vq, &sq->napi); + } } static int virtnet_set_coalesce(struct net_device *dev, @@ -3577,25 +3598,11 @@ static int virtnet_set_coalesce(struct net_device *dev, struct netlink_ext_ack *extack) { struct virtnet_info *vi = netdev_priv(dev); - int ret, queue_number, napi_weight; - bool update_napi = false; - - /* Can't change NAPI weight if the link is up */ - napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0; - for (queue_number = 0; queue_number < vi->max_queue_pairs; queue_number++) { - ret = virtnet_should_update_vq_weight(dev->flags, napi_weight, - vi->sq[queue_number].napi.weight, - &update_napi); - if (ret) - return ret; - - if (update_napi) { - /* All queues that belong to [queue_number, vi->max_queue_pairs] will be - * updated for the sake of simplicity, which might not be necessary - */ - break; - } - } + int ret; + + /* Param tx_frames can be used to switch napi_tx */ + virtnet_switch_napi_tx(vi, 0, vi->max_queue_pairs, + ec->tx_max_coalesced_frames); if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) ret = virtnet_send_notf_coal_cmds(vi, ec); @@ -3605,11 +3612,6 @@ static int virtnet_set_coalesce(struct net_device *dev, if (ret) return ret; - if (update_napi) { - for (; queue_number < vi->max_queue_pairs; queue_number++) - vi->sq[queue_number].napi.weight = napi_weight; - } - return ret; } @@ -3641,19 +3643,13 @@ static int virtnet_set_per_queue_coalesce(struct net_device *dev, struct ethtool_coalesce *ec) { struct virtnet_info *vi = netdev_priv(dev); - int ret, napi_weight; - bool update_napi = false; + int ret; if (queue >= vi->max_queue_pairs) return -EINVAL; - /* Can't change NAPI weight if the link is up */ - napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0; - ret = virtnet_should_update_vq_weight(dev->flags, napi_weight, - vi->sq[queue].napi.weight, - &update_napi); - if (ret) - return ret; + /* Param tx_frames can be used to switch napi_tx */ + virtnet_switch_napi_tx(vi, queue, queue, ec->tx_max_coalesced_frames); if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) ret = virtnet_send_notf_coal_vq_cmds(vi, ec, queue); @@ -3663,9 +3659,6 @@ static int virtnet_set_per_queue_coalesce(struct net_device *dev, if (ret) return ret; - if (update_napi) - vi->sq[queue].napi.weight = napi_weight; - return 0; }