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

[Heng Qi <hengqi@xxxxxxxxxxxxxxxxx>]

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 <danielj@xxxxxxxxxx>
> Reviewed-by: Parav Pandit <parav@xxxxxxxxxx>
> ---
>   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);
>