net/mlx5e: Replace reciprocal_scale in TX select queue function
The TX queue index returned by the fallback function ranges between [0,NUM CHANNELS - 1] if QoS isn't set and [0, (NUM CHANNELS)*(NUM TCs) -1] otherwise. Our HW uses different TC mapping than the fallback function (which is denoted as 'up', user priority) so we only need to extract a channel number out of the returned value. Since (NUM CHANNELS)*(NUM TCs) is a relatively small number, using reciprocal scale almost always returns zero. We instead access the 'txq2sq' table to extract the sq (and with it the channel number) associated with the tx queue, thus getting a more evenly distributed channel number. Perf: Rx/Tx side with Intel(R) Xeon(R) Silver 4108 CPU @ 1.80GHz and ConnectX-5. Used 'iperf' UDP traffic, 10 threads, and priority 5. Before: 0.566Mpps After: 2.37Mpps As expected, releasing the existing bottleneck of steering all traffic to TX queue zero significantly improves transmission rates. Fixes: 7ccdd084 ("net/mlx5e: Fix select queue callback") Signed-off-by: Shay Agroskin <shayag@mellanox.com> Reviewed-by: Tariq Toukan <tariqt@mellanox.com> Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Showing
Please register or sign in to comment