Commit 3c87aedd authored by Maxim Mikityanskiy's avatar Maxim Mikityanskiy Committed by Saeed Mahameed
Browse files

net/mlx5e: Optimize mlx5e_select_queue 



This commit optimizes mlx5e_select_queue for HTB and PTP cases by
short-cutting some checks, without sacrificing performance of the common
non-HTB non-PTP flow.

1. The HTB flow uses the fact that num_tcs == 1 to drop these checks
(it's not possible to attach both mqprio and htb as the root qdisc).
It's also enough to calculate `txq_ix % num_channels` only once, instead
of twice.

2. The PTP flow drops the check for HTB and the second calculation of
`txq_ix % num_channels`.

Signed-off-by: default avatarMaxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: default avatarTariq Toukan <tariqt@nvidia.com>
Signed-off-by: default avatarSaeed Mahameed <saeedm@nvidia.com>
parent ed5f9cf0

drivers/net/ethernet/mellanox/mlx5/core/en/selq.c

+42 −16
Original line number Diff line number Diff line
@@ -164,36 +164,62 @@ u16 mlx5e_select_queue(struct net_device *dev, struct sk_buff *skb, 
	if (unlikely(!selq))

		return 0;



	if (unlikely(selq->is_ptp || selq->is_htb)) {

	if (likely(!selq->is_ptp && !selq->is_htb)) {

		/* No special queues, netdev_pick_tx returns one of the regular ones. */



		txq_ix = netdev_pick_tx(dev, skb, NULL);



		if (selq->num_tcs <= 1)

			return txq_ix;



		up = mlx5e_get_up(priv, skb);



		/* Normalize any picked txq_ix to [0, num_channels),

		 * So we can return a txq_ix that matches the channel and

		 * packet UP.

		 */

		return txq_ix % selq->num_channels + up * selq->num_channels;

	}



	if (unlikely(selq->is_htb)) {

		/* num_tcs == 1, shortcut for PTP */



		txq_ix = mlx5e_select_htb_queue(priv, skb);

		if (txq_ix > 0)

			return txq_ix;

		}



		if (unlikely(selq->is_ptp && mlx5e_use_ptpsq(skb)))

			return mlx5e_select_ptpsq(dev, skb, selq);

			return selq->num_channels;



		txq_ix = netdev_pick_tx(dev, skb, NULL);



		/* Fix netdev_pick_tx() not to choose ptp_channel and HTB txqs.

		 * If they are selected, switch to regular queues.

		 * Driver to select these queues only at mlx5e_select_ptpsq()

		 * and mlx5e_select_htb_queue().

		 */

		if (unlikely(txq_ix >= selq->num_regular_queues))

			txq_ix %= selq->num_regular_queues;

	} else {

		txq_ix = netdev_pick_tx(dev, skb, NULL);

		return txq_ix % selq->num_channels;

	}



	/* PTP is enabled */



	if (mlx5e_use_ptpsq(skb))

		return mlx5e_select_ptpsq(dev, skb, selq);



	txq_ix = netdev_pick_tx(dev, skb, NULL);



	/* Normalize any picked txq_ix to [0, num_channels). Queues in range

	 * [0, num_regular_queues) will be mapped to the corresponding channel

	 * index, so that we can apply the packet's UP (if num_tcs > 1).

	 * If netdev_pick_tx() picks ptp_channel, switch to a regular queue,

	 * because driver should select the PTP only at mlx5e_select_ptpsq().

	 */

	txq_ix %= selq->num_channels;



	if (selq->num_tcs <= 1)

		return txq_ix;



	up = mlx5e_get_up(priv, skb);



	/* Normalize any picked txq_ix to [0, num_channels),

	 * So we can return a txq_ix that matches the channel and

	 * packet UP.

	 */

	return txq_ix % selq->num_channels + up * selq->num_channels;

	return txq_ix + up * selq->num_channels;

}