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Message-ID: <11b9c844-a56e-427f-aab3-3e223d41b165@gmail.com>
Date: Thu, 6 Jun 2024 23:11:57 +0300
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Subject: Re: [RFC net-next v4 2/2] net/mlx5e: Add per queue netdev-genl stats
To: Joe Damato <jdamato@fastly.com>, netdev@vger.kernel.org,
 linux-kernel@vger.kernel.org
Cc: nalramli@fastly.com, Saeed Mahameed <saeedm@nvidia.com>,
 Leon Romanovsky <leon@kernel.org>, "David S. Miller" <davem@davemloft.net>,
 Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>,
 Paolo Abeni <pabeni@redhat.com>, Richard Cochran <richardcochran@gmail.com>,
 "open list:MELLANOX MLX5 core VPI driver" <linux-rdma@vger.kernel.org>,
 Tariq Toukan <tariqt@nvidia.com>
References: <20240604004629.299699-1-jdamato@fastly.com>
 <20240604004629.299699-3-jdamato@fastly.com>
Content-Language: en-US
From: Tariq Toukan <ttoukan.linux@gmail.com>
In-Reply-To: <20240604004629.299699-3-jdamato@fastly.com>
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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;