[PATCH net-next v2 2/2] virtio_net: Add TX stopped and wake counters

[Daniel Jurgens]

Add a tx queue stop and wake counters, they are useful for debugging.

$ ./tools/net/ynl/cli.py --spec netlink/specs/netdev.yaml \
--dump qstats-get --json '{"scope": "queue"}'
...
 {'ifindex': 13,
  'queue-id': 0,
  'queue-type': 'tx',
  'tx-bytes': 14756682850,
  'tx-packets': 226465,
  'tx-stop': 113208,
  'tx-wake': 113208},
 {'ifindex': 13,
  'queue-id': 1,
  'queue-type': 'tx',
  'tx-bytes': 18167675008,
  'tx-packets': 278660,
  'tx-stop': 8632,
  'tx-wake': 8632}]

Signed-off-by: Daniel Jurgens <dani...@nvidia.com>
Reviewed-by: Jiri Pirko <j...@nvidia.com>
---
 drivers/net/virtio_net.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 218a446c4c27..df6121c38a1b 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -95,6 +95,8 @@ struct virtnet_sq_stats {
        u64_stats_t xdp_tx_drops;
        u64_stats_t kicks;
        u64_stats_t tx_timeouts;
+       u64_stats_t stop;
+       u64_stats_t wake;
 };
 
 struct virtnet_rq_stats {
@@ -145,6 +147,8 @@ static const struct virtnet_stat_desc 
virtnet_rq_stats_desc[] = {
 static const struct virtnet_stat_desc virtnet_sq_stats_desc_qstat[] = {
        VIRTNET_SQ_STAT_QSTAT("packets", packets),
        VIRTNET_SQ_STAT_QSTAT("bytes",   bytes),
+       VIRTNET_SQ_STAT_QSTAT("stop",    stop),
+       VIRTNET_SQ_STAT_QSTAT("wake",    wake),
 };
 
 static const struct virtnet_stat_desc virtnet_rq_stats_desc_qstat[] = {
@@ -1014,6 +1018,9 @@ static void check_sq_full_and_disable(struct virtnet_info 
*vi,
         */
        if (sq->vq->num_free < 2+MAX_SKB_FRAGS) {
                netif_stop_subqueue(dev, qnum);
+               u64_stats_update_begin(&sq->stats.syncp);
+               u64_stats_inc(&sq->stats.stop);
+               u64_stats_update_end(&sq->stats.syncp);
                if (use_napi) {
                        if (unlikely(!virtqueue_enable_cb_delayed(sq->vq)))
                                virtqueue_napi_schedule(&sq->napi, sq->vq);
@@ -1022,6 +1029,9 @@ static void check_sq_full_and_disable(struct virtnet_info 
*vi,
                        free_old_xmit(sq, false);
                        if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {
                                netif_start_subqueue(dev, qnum);
+                               u64_stats_update_begin(&sq->stats.syncp);
+                               u64_stats_inc(&sq->stats.wake);
+                               u64_stats_update_end(&sq->stats.syncp);
                                virtqueue_disable_cb(sq->vq);
                        }
                }
@@ -2322,8 +2332,14 @@ static void virtnet_poll_cleantx(struct receive_queue 
*rq)
                        free_old_xmit(sq, true);
                } while (unlikely(!virtqueue_enable_cb_delayed(sq->vq)));
 
-               if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS)
+               if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) {
+                       if (netif_tx_queue_stopped(txq)) {
+                               u64_stats_update_begin(&sq->stats.syncp);
+                               u64_stats_inc(&sq->stats.wake);
+                               u64_stats_update_end(&sq->stats.syncp);
+                       }
                        netif_tx_wake_queue(txq);
+               }
 
                __netif_tx_unlock(txq);
        }
@@ -2473,8 +2489,14 @@ static int virtnet_poll_tx(struct napi_struct *napi, int 
budget)
        virtqueue_disable_cb(sq->vq);
        free_old_xmit(sq, true);
 
-       if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS)
+       if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) {
+               if (netif_tx_queue_stopped(txq)) {
+                       u64_stats_update_begin(&sq->stats.syncp);
+                       u64_stats_inc(&sq->stats.wake);
+                       u64_stats_update_end(&sq->stats.syncp);
+               }
                netif_tx_wake_queue(txq);
+       }
 
        opaque = virtqueue_enable_cb_prepare(sq->vq);
 
@@ -4790,6 +4812,8 @@ static void virtnet_get_base_stats(struct net_device *dev,
 
        tx->bytes = 0;
        tx->packets = 0;
+       tx->stop = 0;
+       tx->wake = 0;
 
        if (vi->device_stats_cap & VIRTIO_NET_STATS_TYPE_TX_BASIC) {
                tx->hw_drops = 0;
-- 
2.45.0