> From: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> Sent: Thursday, May 9, 2024 8:22 PM
> To: Dan Jurgens <danielj@xxxxxxxxxx>
> Cc: mst@xxxxxxxxxx; jasowang@xxxxxxxxxx; xuanzhuo@xxxxxxxxxxxxxxxxx;
> virtualization@xxxxxxxxxxxxxxx; davem@xxxxxxxxxxxxx;
> edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx; Jiri Pirko
> <jiri@xxxxxxxxxx>; Dan Jurgens <danielj@xxxxxxxxxx>;
> netdev@xxxxxxxxxxxxxxx
> 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@xxxxxxxxxx>
> 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@xxxxxxxxxx>
> > Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx>
> > ---
> > 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?
I intentionally only counted the wakes on restarts after stopping the queue.
I don't think counting the initial wake adds any value since it always happens.
>
> 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
> >
