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

[Jiri Pirko]

From: Jiri Pirko <j...@nvidia.com>

Add support for Byte Queue Limits (BQL).

Signed-off-by: Jiri Pirko <j...@nvidia.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