Re: [PATCH net-next 0/1] mlx5: Add netdev-genl queue stats

Joe Damato
2024-05-03T23:53:44Z

On Fri, May 03, 2024 at 02:58:08PM -0700, Jakub Kicinski wrote:
> On Fri, 3 May 2024 11:43:27 -0700 Joe Damato wrote:
> > 1. it includes the PTP stats that I don't include in my qstats, and/or
> > 2. some other reason I don't understand
>
> Can you add the PTP stats to the "base" values?
> I.e. inside mlx5e_get_base_stats()?

I tried adding them to rx and tx and mlx5e_get_base_stats (similar to what
mlx5e_fold_sw_stats64 does) and the test still fails.

Maybe something about the rtnl stats are what's off here and the queue
stats are fine?

FWIW: I spoke with the Mellanox folks off list several weeks ago and they
seemed to suggest skipping the PTP stats made the most sense.

I think at that time I didn't really understand get_base_stats that well,
so maybe we'd have come to a different conclusion then.

FWIW, here's what I tried and the rtnl vs qstat test still failed in
exactly the same way:

--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -5337,10 +5337,25 @@ static void mlx5e_get_base_stats(struct net_device *dev,
rx->packets = 0;
rx->bytes = 0;
rx->alloc_fail = 0;
+ if (priv->rx_ptp_opened) {
+ struct mlx5e_rq_stats *rq_stats = &priv->ptp_stats.rq;
+ rx->packets = rq_stats->packets;
+ rx->bytes = rq_stats->bytes;
+ }
}

tx->packets = 0;
tx->bytes = 0;
+
+ if (priv->tx_ptp_opened) {
+ int i;
+ for (i = 0; i < priv->max_opened_tc; i++) {
+ struct mlx5e_sq_stats *sq_stats = &priv->ptp_stats.sq[i];
+
+ tx->packets += sq_stats->packets;
+ tx->bytes += sq_stats->bytes;
+ }
+ }
}

> We should probably touch up the kdoc a little bit, but it sounds like
> the sort of thing which would fall into the realm of "misc delta"
> values:
>
> diff --git a/include/net/netdev_queues.h b/include/net/netdev_queues.h
> index c7ac4539eafc..f5d9f3ad5b66 100644
> --- a/include/net/netdev_queues.h
> +++ b/include/net/netdev_queues.h
> @@ -59,6 +59,8 @@ struct netdev_queue_stats_tx {
> * statistics will not generally add up to the total number of events for
> * the device. The @get_base_stats callback allows filling in the delta
> * between events for currently live queues and overall device history.
> + * @get_base_stats can also be used to report any miscellaneous packets
> + * transferred outside of the main set of queues used by the networking stack.
> * When the statistics for the entire device are queried, first @get_base_stats
> * is issued to collect the delta, and then a series of per-queue callbacks.
> * Only statistics which are set in @get_base_stats will be reported
>
>
> SG?

I think that sounds good and makes sense, yea. By that definition, then I
should leave the PTP stats as shown above. If you agree, I'll add that
to the v2.

I feel like I should probably wait before sending a v2 with PTP included in
get_base_stats to see if the Mellanox folks have any hints about why rtnl
!= queue stats on mlx5?

What do you think?