Re: [PATCH net-next] virtio_net: Add TX stop and wake counters

[Heng Qi]

在 2024/1/30 下午10:25, Daniel Jurgens 写道:
Add a tx queue stop and wake counters, they are useful for debugging.

        $ ethtool -S ens5f2 | grep 'tx_stop\|tx_wake'
        ...
        tx_queue_1_tx_stop: 16726
        tx_queue_1_tx_wake: 16726
        ...
        tx_queue_8_tx_stop: 1500110
        tx_queue_8_tx_wake: 1500110

Signed-off-by: Daniel Jurgens <dani...@nvidia.com>
Reviewed-by: Parav Pandit <pa...@nvidia.com>
---
  drivers/net/virtio_net.c | 26 ++++++++++++++++++++++++--
  1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 3cb8aa193884..7e3c31ceaf7e 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -88,6 +88,8 @@ struct virtnet_sq_stats {
        u64_stats_t xdp_tx_drops;
        u64_stats_t kicks;
        u64_stats_t tx_timeouts;
+       u64_stats_t tx_stop;
+       u64_stats_t tx_wake;
  };

Hi Daniel!

tx_stop/wake only counts the status in the I/O path.
Do the status of virtnet_config_changed_work and virtnet_tx_resize need 
to be counted?

Thanks,
Heng

  
  struct virtnet_rq_stats {
@@ -112,6 +114,8 @@ static const struct virtnet_stat_desc 
virtnet_sq_stats_desc[] = {
        { "xdp_tx_drops",     VIRTNET_SQ_STAT(xdp_tx_drops) },
        { "kicks",            VIRTNET_SQ_STAT(kicks) },
        { "tx_timeouts",      VIRTNET_SQ_STAT(tx_timeouts) },
+       { "tx_stop",          VIRTNET_SQ_STAT(tx_stop) },
+       { "tx_wake",          VIRTNET_SQ_STAT(tx_wake) },
  };
  
  static const struct virtnet_stat_desc virtnet_rq_stats_desc[] = {
@@ -843,6 +847,9 @@ 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.tx_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);
@@ -851,6 +858,9 @@ static void check_sq_full_and_disable(struct virtnet_info 
*vi,
                        free_old_xmit_skbs(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.tx_wake);
+                               u64_stats_update_end(&sq->stats.syncp);
                                virtqueue_disable_cb(sq->vq);
                        }
                }
@@ -2163,8 +2173,14 @@ static void virtnet_poll_cleantx(struct receive_queue 
*rq)
                        free_old_xmit_skbs(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.tx_wake);
+                               u64_stats_update_end(&sq->stats.syncp);
+                       }
                        netif_tx_wake_queue(txq);
+               }
  
  		__netif_tx_unlock(txq);
        }
@@ -2310,8 +2326,14 @@ static int virtnet_poll_tx(struct napi_struct *napi, int 
budget)
        virtqueue_disable_cb(sq->vq);
        free_old_xmit_skbs(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.tx_wake);
+                       u64_stats_update_end(&sq->stats.syncp);
+               }
                netif_tx_wake_queue(txq);
+       }
  
  	opaque = virtqueue_enable_cb_prepare(sq->vq);