Re: [RFC net-next v4 2/2] net/mlx5e: Add per queue netdev-genl stats

Tariq Toukan
2024-06-06T20:12:02Z

On 04/06/2024 3:46, Joe Damato wrote:
> ./cli.py --spec netlink/specs/netdev.yaml \
> --dump qstats-get --json '{"scope": "queue"}'
>
> ...snip
>
> {'ifindex': 7,
> 'queue-id': 62,
> 'queue-type': 'rx',
> 'rx-alloc-fail': 0,
> 'rx-bytes': 105965251,
> 'rx-packets': 179790},
> {'ifindex': 7,
> 'queue-id': 0,
> 'queue-type': 'tx',
> 'tx-bytes': 9402665,
> 'tx-packets': 17551},
>
> ...snip
>
> Also tested with the script tools/testing/selftests/drivers/net/stats.py
> in several scenarios to ensure stats tallying was correct:
>
> - on boot (default queue counts)
> - adjusting queue count up or down (ethtool -L eth0 combined ...)
>
> The tools/testing/selftests/drivers/net/stats.py brings the device up,
> so to test with the device down, I did the following:
>
> $ ip link show eth4
> 7: eth4: <BROADCAST,MULTICAST> mtu 9000 qdisc mq state DOWN [..snip..]
> [..snip..]
>
> $ cat /proc/net/dev | grep eth4
> eth4: 235710489 434811 [..snip rx..] 2878744 21227 [..snip tx..]
>
> $ ./cli.py --spec ../../../Documentation/netlink/specs/netdev.yaml \
> --dump qstats-get --json '{"ifindex": 7}'
> [{'ifindex': 7,
> 'rx-alloc-fail': 0,
> 'rx-bytes': 235710489,
> 'rx-packets': 434811,
> 'tx-bytes': 2878744,
> 'tx-packets': 21227}]
>
> Compare the values in /proc/net/dev match the output of cli for the same
> device, even while the device is down.
>
> Note that while the device is down, per queue stats output nothing
> (because the device is down there are no queues):

This part is not true anymore.

>
> $ ./cli.py --spec ../../../Documentation/netlink/specs/netdev.yaml \
> --dump qstats-get --json '{"scope": "queue", "ifindex": 7}'
> []
>
> Signed-off-by: Joe Damato <jdamato@fastly.com>
> ---
> .../net/ethernet/mellanox/mlx5/core/en_main.c | 138 ++++++++++++++++++
> 1 file changed, 138 insertions(+)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> index d03fd1c98eb6..76d64bbcf250 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> @@ -39,6 +39,7 @@
> #include <linux/debugfs.h>
> #include <linux/if_bridge.h>
> #include <linux/filter.h>
> +#include <net/netdev_queues.h>
> #include <net/page_pool/types.h>
> #include <net/pkt_sched.h>
> #include <net/xdp_sock_drv.h>
> @@ -5279,6 +5280,142 @@ static bool mlx5e_tunnel_any_tx_proto_supported(struct mlx5_core_dev *mdev)
> return (mlx5_vxlan_allowed(mdev->vxlan) || mlx5_geneve_tx_allowed(mdev));
> }
>
> +static void mlx5e_get_queue_stats_rx(struct net_device *dev, int i,
> + struct netdev_queue_stats_rx *stats)
> +{
> + struct mlx5e_priv *priv = netdev_priv(dev);
> + struct mlx5e_channel_stats *channel_stats;
> + struct mlx5e_rq_stats *xskrq_stats;
> + struct mlx5e_rq_stats *rq_stats;
> +
> + ASSERT_RTNL();
> + if (mlx5e_is_uplink_rep(priv))
> + return;
> +
> + /* ptp was ever opened, is currently open, and channel index matches i
> + * then export stats
> + */
> + if (priv->rx_ptp_opened && priv->channels.ptp) {
> + if (test_bit(MLX5E_PTP_STATE_RX, priv->channels.ptp->state) &&
> + priv->channels.ptp->rq.ix == i) {

PTP RQ index is naively assigned to zero:
rq->ix = MLX5E_PTP_CHANNEL_IX;

but this isn't to be used as the stats index.
Today, the PTP-RQ has no matcing rxq in the kernel level.
i.e. turning PTP-RQ on won't add a kernel-level RXQ to the
real_num_rx_queues.
Maybe we better do.
If not, and the current state is kept, the best we can do is let the
PTP-RQ naively contribute its queue-stat to channel 0.

> + rq_stats = &priv->ptp_stats.rq;
> + stats->packets = rq_stats->packets;
> + stats->bytes = rq_stats->bytes;
> + stats->alloc_fail = rq_stats->buff_alloc_err;
> + return;
> + }
> + }
> +
> + channel_stats = priv->channel_stats[i];
> + xskrq_stats = &channel_stats->xskrq;
> + rq_stats = &channel_stats->rq;
> +
> + stats->packets = rq_stats->packets + xskrq_stats->packets;
> + stats->bytes = rq_stats->bytes + xskrq_stats->bytes;
> + stats->alloc_fail = rq_stats->buff_alloc_err +
> + xskrq_stats->buff_alloc_err;
> +}
> +
> +static void mlx5e_get_queue_stats_tx(struct net_device *dev, int i,
> + struct netdev_queue_stats_tx *stats)
> +{
> + struct mlx5e_priv *priv = netdev_priv(dev);
> + struct mlx5e_sq_stats *sq_stats;
> +
> + ASSERT_RTNL();
> + /* no special case needed for ptp htb etc since txq2sq_stats is kept up
> + * to date for active sq_stats, otherwise get_base_stats takes care of
> + * inactive sqs.
> + */
> + sq_stats = priv->txq2sq_stats[i];
> + stats->packets = sq_stats->packets;
> + stats->bytes = sq_stats->bytes;
> +}
> +
> +static void mlx5e_get_base_stats(struct net_device *dev,
> + struct netdev_queue_stats_rx *rx,
> + struct netdev_queue_stats_tx *tx)
> +{
> + struct mlx5e_priv *priv = netdev_priv(dev);
> + int i, tc;
> +
> + ASSERT_RTNL();
> + if (!mlx5e_is_uplink_rep(priv)) {
> + rx->packets = 0;
> + rx->bytes = 0;
> + rx->alloc_fail = 0;
> +
> + for (i = priv->channels.params.num_channels; i < priv->stats_nch; i++) {
> + struct netdev_queue_stats_rx rx_i = {0};
> +
> + mlx5e_get_queue_stats_rx(dev, i, &rx_i);
> +
> + rx->packets += rx_i.packets;
> + rx->bytes += rx_i.bytes;
> + rx->alloc_fail += rx_i.alloc_fail;
> + }
> +
> + if (priv->rx_ptp_opened) {
> + /* if PTP was opened, but is not currently open, then
> + * report the stats here. otherwise,
> + * mlx5e_get_queue_stats_rx will get it
> + */

We shouldn't care if the RQ is currently open. The stats are always there.
This applies to all RQs and SQs.

> + if (priv->channels.ptp &&
> + !test_bit(MLX5E_PTP_STATE_RX, priv->channels.ptp->state)) {
> + 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;
> +
> + for (i = 0; i < priv->stats_nch; i++) {
> + struct mlx5e_channel_stats *channel_stats = priv->channel_stats[i];
> +
> + /* while iterating through all channels [0, stats_nch], there
> + * are two cases to handle:
> + *
> + * 1. the channel is available, so sum only the unavailable TCs
> + * [mlx5e_get_dcb_num_tc, max_opened_tc).
> + *
> + * 2. the channel is unavailable, so sum all TCs [0, max_opened_tc).
> + */

Even if the channel is not available, mlx5e_get_queue_stats_tx()
accesses and returns its stats.
Here you need to only cover SQs that have no mapping in range
[0..real_num_tx_queues - 1].

> + if (i < priv->channels.params.num_channels)
> + tc = mlx5e_get_dcb_num_tc(&priv->channels.params);
> + else
> + tc = 0;
> +
> + for (; tc < priv->max_opened_tc; tc++) {
> + struct mlx5e_sq_stats *sq_stats = &channel_stats->sq[tc];
> +
> + tx->packets += sq_stats->packets;
> + tx->bytes += sq_stats->bytes;
> + }
> + }
> +
> + if (priv->tx_ptp_opened) {
> + /* only report PTP TCs if it was opened but is now closed */
> + if (priv->channels.ptp && !test_bit(MLX5E_PTP_STATE_TX, priv->channels.ptp->state)) {
> + for (tc = 0; tc < priv->channels.ptp->num_tc; tc++) {
> + struct mlx5e_sq_stats *sq_stats = &priv->ptp_stats.sq[tc];
> +
> + tx->packets += sq_stats->packets;
> + tx->bytes += sq_stats->bytes;
> + }
> + }
> + }
> +}
> +
> +static const struct netdev_stat_ops mlx5e_stat_ops = {
> + .get_queue_stats_rx = mlx5e_get_queue_stats_rx,
> + .get_queue_stats_tx = mlx5e_get_queue_stats_tx,
> + .get_base_stats = mlx5e_get_base_stats,
> +};
> +
> static void mlx5e_build_nic_netdev(struct net_device *netdev)
> {
> struct mlx5e_priv *priv = netdev_priv(netdev);
> @@ -5296,6 +5433,7 @@ static void mlx5e_build_nic_netdev(struct net_device *netdev)
>
> netdev->watchdog_timeo = 15 * HZ;
>
> + netdev->stat_ops = &mlx5e_stat_ops;
> netdev->ethtool_ops = &mlx5e_ethtool_ops;
>
> netdev->vlan_features |= NETIF_F_SG;