Re: [dpdk-dev] [PATCH V2] app/testpmd: support Tx mbuf free on demand cmd

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 3/5/2021 9:57 AM, Lijun Ou wrote:
> From: Chengwen Feng <fengchengwen@huawei.com>
> 
> This patch support tx_done_cleanup command:
> tx_done_cleanup port (port_id) (queue_id) (free_cnt)
> 
> Users must make sure there are no concurrent access to the same Tx
> queue (like rte_eth_tx_burst, rte_eth_dev_tx_queue_stop and so on)
> this command executed.
> 

Hi Lijun,

Is the intention to test the PMD implementation?
As you highlighted the API is for the datapath, a command for it is not easy to 
use, not sure how useful it will be.
Perhaps it can be option to use this API in a forwarding engine, like 'txonly', 
controlled by a command, but again not sure what to observe/measure etc..

> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
> Signed-off-by: Lijun Ou <oulijun@huawei.com>
> ---
> V1->V2:
> - use Tx instead of TX
> - add note in doc
> ---
>   app/test-pmd/cmdline.c                      | 91 +++++++++++++++++++++++++++++
>   doc/guides/rel_notes/release_21_05.rst      |  2 +
>   doc/guides/testpmd_app_ug/testpmd_funcs.rst | 11 ++++
>   3 files changed, 104 insertions(+)
> 
> diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c
> index 14110eb..4df0c32 100644
> --- a/app/test-pmd/cmdline.c
> +++ b/app/test-pmd/cmdline.c
> @@ -36,6 +36,7 @@
>   #include <rte_pci.h>
>   #include <rte_ether.h>
>   #include <rte_ethdev.h>
> +#include <rte_ethdev_driver.h>

This header for PMDs to include, applications shouldn't include this, including 
this means you are accessing dpdk internals which you shouldn't access.

>   #include <rte_string_fns.h>
>   #include <rte_devargs.h>
>   #include <rte_flow.h>
> @@ -675,6 +676,9 @@ static void cmd_help_long_parsed(void *parsed_result,
>   			"set port (port_id) ptype_mask (ptype_mask)\n"
>   			"    set packet types classification for a specific port\n\n"
>   
> +			"tx_done_cleanup (port_id) (queue_id) (free_cnt)\n"
> +			"    Cleanup a Tx queue's mbuf on a port\n\n"
> +
>   			"set port (port_id) queue-region region_id (value) "
>   			"queue_start_index (value) queue_num (value)\n"
>   			"    Set a queue region on a port\n\n"
> @@ -16910,6 +16914,92 @@ cmdline_parse_inst_t cmd_showport_macs = {
>   	},
>   };
>   
> +/* *** tx_done_cleanup *** */
> +struct cmd_tx_done_cleanup_result {
> +	cmdline_fixed_string_t clean;
> +	cmdline_fixed_string_t port;
> +	uint16_t port_id;
> +	uint16_t queue_id;
> +	uint32_t free_cnt;
> +};
> +
> +static void
> +cmd_tx_done_cleanup_parsed(void *parsed_result,
> +			   __rte_unused struct cmdline *cl,
> +			   __rte_unused void *data)
> +{
> +	struct cmd_tx_done_cleanup_result *res = parsed_result;
> +	struct rte_eth_dev *dev;
> +	uint16_t port_id = res->port_id;
> +	uint16_t queue_id = res->queue_id;
> +	uint32_t free_cnt = res->free_cnt;
> +	int ret;
> +
> +	if (!rte_eth_dev_is_valid_port(port_id)) {
> +		printf("Invalid port_id %u\n", port_id);
> +		return;
> +	}
> +
> +	dev = &rte_eth_devices[port_id];

Similar to above comment 'rte_eth_devices' is the internal variable, 
applications should not access it directly.

> +	if (queue_id >= dev->data->nb_tx_queues) {
> +		printf("Invalid Tx queue_id %u\n", queue_id);
> +		return;
> +	}
> +

Number of the queues can be get via 'rte_eth_dev_info_get()'.

> +	if (dev->data->tx_queue_state[queue_id] !=
> +		RTE_ETH_QUEUE_STATE_STARTED) {
> +		printf("Tx queue_id %u not started!\n", queue_id);
> +		return;
> +	}
> +

I am not sure if we have an API to get this information, if there is a need from 
application to get this data we should consider adding a new API. cc'ed Andrew 
and Thomas.

> +	/*
> +	 * rte_eth_tx_done_cleanup is a dataplane API, user must make sure
> +	 * there are no concurrent access to the same Tx queue (like
> +	 * rte_eth_tx_burst, rte_eth_dev_tx_queue_stop and so on) when this API
> +	 * called.
> +	 */
> +	ret = rte_eth_tx_done_cleanup(port_id, queue_id, free_cnt);
> +	if (ret < 0) {
> +		printf("Failed to cleanup mbuf for port %u Tx queue %u "
> +		       "error desc: %s(%d)\n",
> +		       port_id, queue_id, strerror(-ret), ret);
> +		return;
> +	}
> +
> +	printf("Cleanup port %u Tx queue %u mbuf nums: %u\n",
> +	       port_id, queue_id, ret);
> +}
> +
> +cmdline_parse_token_string_t cmd_tx_done_cleanup_clean =
> +	TOKEN_STRING_INITIALIZER(struct cmd_tx_done_cleanup_result, clean,
> +				 "tx_done_cleanup");
> +cmdline_parse_token_string_t cmd_tx_done_cleanup_port =
> +	TOKEN_STRING_INITIALIZER(struct cmd_tx_done_cleanup_result, port,
> +				 "port");
> +cmdline_parse_token_num_t cmd_tx_done_cleanup_port_id =
> +	TOKEN_NUM_INITIALIZER(struct cmd_tx_done_cleanup_result, port_id,
> +			      UINT16);
> +cmdline_parse_token_num_t cmd_tx_done_cleanup_queue_id =
> +	TOKEN_NUM_INITIALIZER(struct cmd_tx_done_cleanup_result, queue_id,
> +			      UINT16);
> +cmdline_parse_token_num_t cmd_tx_done_cleanup_free_cnt =
> +	TOKEN_NUM_INITIALIZER(struct cmd_tx_done_cleanup_result, free_cnt,
> +			      UINT32);
> +
> +cmdline_parse_inst_t cmd_tx_done_cleanup = {
> +	.f = cmd_tx_done_cleanup_parsed,
> +	.data = NULL,
> +	.help_str = "tx_done_cleanup port <port_id> <queue_id> <free_cnt>",
> +	.tokens = {
> +		(void *)&cmd_tx_done_cleanup_clean,
> +		(void *)&cmd_tx_done_cleanup_port,
> +		(void *)&cmd_tx_done_cleanup_port_id,
> +		(void *)&cmd_tx_done_cleanup_queue_id,
> +		(void *)&cmd_tx_done_cleanup_free_cnt,
> +		NULL,
> +	},
> +};
> +
>   /* ******************************************************************************** */
>   
>   /* list of instructions */
> @@ -17035,6 +17125,7 @@ cmdline_parse_ctx_t main_ctx[] = {
>   	(cmdline_parse_inst_t *)&cmd_config_rss_reta,
>   	(cmdline_parse_inst_t *)&cmd_showport_reta,
>   	(cmdline_parse_inst_t *)&cmd_showport_macs,
> +	(cmdline_parse_inst_t *)&cmd_tx_done_cleanup,
>   	(cmdline_parse_inst_t *)&cmd_config_burst,
>   	(cmdline_parse_inst_t *)&cmd_config_thresh,
>   	(cmdline_parse_inst_t *)&cmd_config_threshold,
> diff --git a/doc/guides/rel_notes/release_21_05.rst b/doc/guides/rel_notes/release_21_05.rst
> index 23f7f0b..8077573 100644
> --- a/doc/guides/rel_notes/release_21_05.rst
> +++ b/doc/guides/rel_notes/release_21_05.rst
> @@ -69,6 +69,8 @@ New Features
>   
>     * Added command to display Rx queue used descriptor count.
>       ``show port (port_id) rxq (queue_id) desc used count``
> +  * Added command to cleanup a Tx queue's mbuf on a port.
> +    ``tx_done_cleanup port <port_id> <queue_id> <free_cnt>``
>   
>   
>   Removed Items
> diff --git a/doc/guides/testpmd_app_ug/testpmd_funcs.rst b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> index f59eb8a..fa49e58 100644
> --- a/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> +++ b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> @@ -272,6 +272,17 @@ and ready to be processed by the driver on a given RX queue::
>   
>      testpmd> show port (port_id) rxq (queue_id) desc used count
>   
> +cleanup txq mbufs
> +~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +Request the driver to free mbufs currently cached by the driver for a given port's
> +Tx queue::
> +   testpmd> tx_done_cleanup port (port_id) (queue_id) (free_cnt)
> +
> +.. note::
> +   This command is dangerous, users must make sure there are no cucurrent access to
> +   the same Tx queue (link rte_eth_tx_burst, rte_eth_dev_tx_queue_stop and so on).
> +
>   show config
>   ~~~~~~~~~~~
>   
>