> From: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> Sent: Friday, May 10, 2024 1:48 AM
> To: Dan Jurgens <danielj@xxxxxxxxxx>
> Cc: mst@xxxxxxxxxx; jasowang@xxxxxxxxxx; virtualization@xxxxxxxxxxxxxxx;
> davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx;
> pabeni@xxxxxxxxxx; Jiri Pirko <jiri@xxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx
> Subject: Re: RE: [PATCH net-next 2/2] virtio_net: Add TX stopped and wake
> counters
>
> On Fri, 10 May 2024 03:35:51 +0000, Dan Jurgens <danielj@xxxxxxxxxx>
> wrote:
> > > 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.
>
> 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.
I think we should. We incremented the stop counter. If they get out sync wake loses any functionality.
>
> 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) {
> > > > + 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
> > > >
> >
