On Fri, 10 May 2024 03:35:51 +, Dan Jurgens wrote:
> > From: Xuan Zhuo
> > Sent: Thursday, May 9, 2024 8:22 PM
> > To: Dan Jurgens
> > Cc: m...@redhat.com; jasow...@redhat.com; xuanz...@linux.alibaba.com;
> > virtualizat...@lists.linux.dev; da...@davemloft.net;
> > eduma...@google.com; k...@kernel.org; pab...@redhat.com; Jiri Pirko
> > ; Dan Jurgens ;
> > netdev@vger.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
> > 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
> > > Reviewed-by: Jiri Pirko
> > > ---
> > > 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.
Here, we start the queue immediately after the queue is stopped.
So for the upper layer, the queue "has not" changed the status,
I think we do not need to update the wake counter.
Thanks.
>
> >
> > 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) {
> > > +
