Re: [PATCH v7] app/testpmd: add Host Shaper command

[Thomas Monjalon <thomas@monjalon.net>]

Few comments below,

14/06/2022 14:01, Spike Du:
> Add command line options to support host shaper configure.
> - Command syntax:
>   mlx5 set port <port_id> host_shaper avail_thresh_triggered <0|1> rate
> <rate_num>
> 
> - Example commands:
> To enable avail_thresh_triggered on port 1 and disable current host
> shaper:
> testpmd> mlx5 set port 1 host_shaper avail_thresh_triggered 1 rate 0
> 
> To disable avail_thresh_triggered and current host shaper on port 1:
> testpmd> mlx5 set port 1 host_shaper avail_thresh_triggered 0 rate 0
> 
> The rate unit is 100Mbps.
> To disable avail_thresh_triggered and configure a shaper of 5Gbps on
> port 1:
> testpmd> mlx5 set port 1 host_shaper avail_thresh_triggered 0 rate 50
> 
> Add sample code to handle rxq available descriptor threshold event, it
> delays a while so that rxq empties, then disables host shaper and
> rearms available descriptor threshold event.
> 
> Signed-off-by: Spike Du <spiked@nvidia.com>
[...]
> @@ -3659,6 +3662,10 @@ struct pmd_test_command {
>  				break;
>  			printf("Received avail_thresh event, port:%d rxq_id:%d\n",
>  			       port_id, rxq_id);
> +
> +#ifdef RTE_NET_MLX5
> +			mlx5_test_avail_thresh_event_handler(port_id, rxq_id);
> +#endif

This function includes a check of the driver in use for the port,
so I assume it is OK to call it unconditionally here.

[...]
> +How to use available descriptor threshold and Host Shaper
> +------------------------------

Underlining should be of same size as the title.

> +
> +There are sample command lines to configure available descriptor threshold in testpmd.

Simpler:
There is a command to configure available descriptor threshold in testpmd.

You could add a link here to the doc of the command.

> +Testpmd also contains sample logic to handle available descriptor threshold event.
> +The typical workflow is: testpmd configure available descriptor threshold for Rx queues, enable
> +avail_thresh_triggered in host shaper and register a callback, when traffic from host is
> +too high and Rx queue emptiness is below available descriptor threshold, PMD receives an event and
> +firmware configures a 100Mbps shaper on host port automatically, then PMD call
> +the callback registered previously, which will delay a while to let Rx queue
> +empty, then disable host shaper.
> +
> +Let's assume we have a simple Blue Field 2 setup: port 0 is uplink, port 1

There's no space in BlueField.

> +is VF representor. Each port has 2 Rx queues.
> +In order to control traffic from host to ARM, we can enable available descriptor threshold in testpmd by:
> +
> +.. code-block:: console
> +
> +   testpmd> mlx5 set port 1 host_shaper avail_thresh_triggered 1 rate 0
> +   testpmd> set port 1 rxq 0 avail_thresh 70
> +   testpmd> set port 1 rxq 1 avail_thresh 70
> +
> +The first command disables current host shaper, and enables available descriptor threshold triggered mode.
> +The left commands configure available descriptor threshold to 70% of Rx queue size for both Rx queues,

left -> other

> +When traffic from host is too high, you can see testpmd console prints log
> +about available descriptor threshold event receiving, then host shaper is disabled.
> +The traffic rate from host is controlled and less drop happens in Rx queues.
> +
> +When disable available descriptor threshold and avail_thresh_triggered, we can invoke below commands in testpmd:

Reword:
The threshold event and shaper can be disabled like this:

> +
> +.. code-block:: console
> +
> +   testpmd> mlx5 set port 1 host_shaper avail_thresh_triggered 0 rate 0
> +   testpmd> set port 1 rxq 0 avail_thresh 0
> +   testpmd> set port 1 rxq 1 avail_thresh 0
> +
> +It's recommended an application disables available descriptor threshold and avail_thresh_triggered before exit,
> +if it enables them before.
> +
> +We can also configure the shaper with a value, the rate unit is 100Mbps, below
> +command sets current shaper to 5Gbps and disables avail_thresh_triggered.
> +
> +.. code-block:: console
> +
> +   testpmd> mlx5 set port 1 host_shaper avail_thresh_triggered 0 rate 50