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>
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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