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

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Message-ID: <1715304096.399735-3-xuanzhuo@linux.alibaba.com>
Date: Fri, 10 May 2024 09:21:36 +0800
From: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To: Daniel Jurgens <danielj@...dia.com>
Cc: <mst@...hat.com>,
 <jasowang@...hat.com>,
 <xuanzhuo@...ux.alibaba.com>,
 <virtualization@...ts.linux.dev>,
 <davem@...emloft.net>,
 <edumazet@...gle.com>,
 <kuba@...nel.org>,
 <pabeni@...hat.com>,
 <jiri@...dia.com>,
 Daniel Jurgens <danielj@...dia.com>,
 <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 2/2] virtio_net: Add TX stopped and wake counters

On Thu, 9 May 2024 11:32:16 -0500, Daniel Jurgens <danielj@...dia.com> wrote:
> 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 <danielj@...dia.com>
> Reviewed-by: Jiri Pirko <jiri@...dia.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);

How about introduce two helpers to wrap
netif_tx_queue_stopped and netif_start_subqueue?

>  		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);

If we start the queue immediately, should we update the counter?

Thanks.

>  				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;
> --
> 2.44.0
>