net/mlx5e: HTB, move ids to selq_params struct

HTB id fields are needed for selecting queue. Moving them to the
selq_params struct will simplify synchronization between control flow
and mlx5e_select

net/mlx5e: HTB, move ids to selq_params struct

HTB id fields are needed for selecting queue. Moving them to the
selq_params struct will simplify synchronization between control flow
and mlx5e_select_queues and will keep the IDs in the hot cacheline of
mlx5e_selq_params.

Replace mlx5e_selq_prepare() with separate functions that change subsets
of parameters, while keeping the rest.

This also will be useful to hide mlx5e_htb structure from the rest of the
driver in a later patch in this series.

Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Moshe Tal <moshet@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Maxim Mikityanskiy <maximmi@nvidia.com>

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net/mlx5e: Optimize modulo in mlx5e_select_queue

To improve the performance of the modulo operation (%), it's replaced by
a subtracting the divisor in a loop. The modulo is used to fix up an
out-of-

net/mlx5e: Optimize modulo in mlx5e_select_queue

To improve the performance of the modulo operation (%), it's replaced by
a subtracting the divisor in a loop. The modulo is used to fix up an
out-of-bounds value that might be returned by netdev_pick_tx or to
convert the queue number to the channel number when num_tcs > 1. Both
situations are unlikely, because XPS is configured not to pick higher
queues (qid >= num_channels) by default, so under normal circumstances
the flow won't go inside the loop, and it will be faster than %.

num_tcs == 8 adds at most 7 iterations to the loop. PTP adds at most 1
iteration to the loop. HTB would add at most 256 iterations (when
num_channels == 1), so there is an additional boundary check in the HTB
flow, which falls back to % if more than 7 iterations are expected.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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net/mlx5e: Move mlx5e_select_queue to en/selq.c

This commit moves mlx5e_select_queue and all stuff related to
ndo_select_queue to en/selq.c to put all stuff working with selq into a
separate file.

net/mlx5e: Move mlx5e_select_queue to en/selq.c

This commit moves mlx5e_select_queue and all stuff related to
ndo_select_queue to en/selq.c to put all stuff working with selq into a
separate file.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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net/mlx5e: Introduce select queue parameters

ndo_select_queue can be called at any time, and there is no way to stop
the kernel from calling it to synchronize with configuration changes
(real_num_tx

net/mlx5e: Introduce select queue parameters

ndo_select_queue can be called at any time, and there is no way to stop
the kernel from calling it to synchronize with configuration changes
(real_num_tx_queues, num_tc). This commit introduces an internal way in
mlx5e to sync mlx5e_select_queue() with these changes. The configuration
needed by this function is stored in a struct mlx5e_selq_params, which
is modified and accessed in an atomic way using RCU methods. The whole
ndo_select_queue is called under an RCU lock, providing the necessary
guarantees.

The parameters stored in the new struct mlx5e_selq_params should only be
used from inside mlx5e_select_queue. It's the minimal set of parameters
needed for mlx5e_select_queue to do its job efficiently, derived from
parameters stored elsewhere. That means that when the configuration
change, mlx5e_selq_params may need to be updated. In such cases, the
mlx5e_selq_prepare/mlx5e_selq_apply API should be used.

struct mlx5e_selq contains two slots for the params: active and standby.
mlx5e_selq_prepare updates the standby slot, and mlx5e_selq_apply swaps
the slots in a safe atomic way using the RCU API. It integrates well
with the open/activate stages of the configuration change flow.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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