netdev - [patch net-next] virtio_net: add support for Byte Queue Limits

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Message-ID: <20240509114615.317450-1-jiri@resnulli.us>
Date: Thu,  9 May 2024 13:46:15 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	mst@...hat.com,
	jasowang@...hat.com,
	xuanzhuo@...ux.alibaba.com,
	virtualization@...ts.linux.dev,
	ast@...nel.org,
	daniel@...earbox.net,
	hawk@...nel.org,
	john.fastabend@...il.com
Subject: [patch net-next] virtio_net: add support for Byte Queue Limits

From: Jiri Pirko <jiri@...dia.com>

Add support for Byte Queue Limits (BQL).

Signed-off-by: Jiri Pirko <jiri@...dia.com>
---
 drivers/net/virtio_net.c | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 218a446c4c27..c53d6dc6d332 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -84,7 +84,9 @@ struct virtnet_stat_desc {
 
 struct virtnet_sq_free_stats {
 	u64 packets;
+	u64 xdp_packets;
 	u64 bytes;
+	u64 xdp_bytes;
 };
 
 struct virtnet_sq_stats {
@@ -512,19 +514,19 @@ static void __free_old_xmit(struct send_queue *sq, bool in_napi,
 	void *ptr;
 
 	while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
-		++stats->packets;
-
 		if (!is_xdp_frame(ptr)) {
 			struct sk_buff *skb = ptr;
 
 			pr_debug("Sent skb %p\n", skb);
 
+			stats->packets++;
 			stats->bytes += skb->len;
 			napi_consume_skb(skb, in_napi);
 		} else {
 			struct xdp_frame *frame = ptr_to_xdp(ptr);
 
-			stats->bytes += xdp_get_frame_len(frame);
+			stats->xdp_packets++;
+			stats->xdp_bytes += xdp_get_frame_len(frame);
 			xdp_return_frame(frame);
 		}
 	}
@@ -965,7 +967,8 @@ static void virtnet_rq_unmap_free_buf(struct virtqueue *vq, void *buf)
 	virtnet_rq_free_buf(vi, rq, buf);
 }
 
-static void free_old_xmit(struct send_queue *sq, bool in_napi)
+static void free_old_xmit(struct send_queue *sq, struct netdev_queue *txq,
+			  bool in_napi)
 {
 	struct virtnet_sq_free_stats stats = {0};
 
@@ -974,9 +977,11 @@ static void free_old_xmit(struct send_queue *sq, bool in_napi)
 	/* Avoid overhead when no packets have been processed
 	 * happens when called speculatively from start_xmit.
 	 */
-	if (!stats.packets)
+	if (!stats.packets && !stats.xdp_packets)
 		return;
 
+	netdev_tx_completed_queue(txq, stats.packets, stats.bytes);
+
 	u64_stats_update_begin(&sq->stats.syncp);
 	u64_stats_add(&sq->stats.bytes, stats.bytes);
 	u64_stats_add(&sq->stats.packets, stats.packets);
@@ -1013,13 +1018,15 @@ static void check_sq_full_and_disable(struct virtnet_info *vi,
 	 * early means 16 slots are typically wasted.
 	 */
 	if (sq->vq->num_free < 2+MAX_SKB_FRAGS) {
-		netif_stop_subqueue(dev, qnum);
+		struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum);
+
+		netif_tx_stop_queue(txq);
 		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(sq, false);
+			free_old_xmit(sq, txq, false);
 			if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {
 				netif_start_subqueue(dev, qnum);
 				virtqueue_disable_cb(sq->vq);
@@ -2319,7 +2326,7 @@ static void virtnet_poll_cleantx(struct receive_queue *rq)
 
 		do {
 			virtqueue_disable_cb(sq->vq);
-			free_old_xmit(sq, true);
+			free_old_xmit(sq, txq, true);
 		} while (unlikely(!virtqueue_enable_cb_delayed(sq->vq)));
 
 		if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS)
@@ -2471,7 +2478,7 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget)
 	txq = netdev_get_tx_queue(vi->dev, index);
 	__netif_tx_lock(txq, raw_smp_processor_id());
 	virtqueue_disable_cb(sq->vq);
-	free_old_xmit(sq, true);
+	free_old_xmit(sq, txq, true);
 
 	if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS)
 		netif_tx_wake_queue(txq);
@@ -2553,7 +2560,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct send_queue *sq = &vi->sq[qnum];
 	int err;
 	struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum);
-	bool kick = !netdev_xmit_more();
+	bool xmit_more = netdev_xmit_more();
 	bool use_napi = sq->napi.weight;
 
 	/* Free up any pending old buffers before queueing new ones. */
@@ -2561,9 +2568,9 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
 		if (use_napi)
 			virtqueue_disable_cb(sq->vq);
 
-		free_old_xmit(sq, false);
+		free_old_xmit(sq, txq, false);
 
-	} while (use_napi && kick &&
+	} while (use_napi && !xmit_more &&
 	       unlikely(!virtqueue_enable_cb_delayed(sq->vq)));
 
 	/* timestamp packet in software */
@@ -2592,7 +2599,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	check_sq_full_and_disable(vi, dev, sq);
 
-	if (kick || netif_xmit_stopped(txq)) {
+	if (__netdev_tx_sent_queue(txq, skb->len, xmit_more)) {
 		if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {
 			u64_stats_update_begin(&sq->stats.syncp);
 			u64_stats_inc(&sq->stats.kicks);
-- 
2.44.0