diff mbox series

[V4] app/testpmd: support Tx mbuf free on demand cmd

Message ID 1618835784-57993-1-git-send-email-oulijun@huawei.com (mailing list archive)
State Changes Requested
Delegated to: Ferruh Yigit
Headers show
Series [V4] app/testpmd: support Tx mbuf free on demand cmd | expand

Checks

Context Check Description
ci/github-robot fail github build: failed
ci/travis-robot fail travis build: failed
ci/Intel-compilation fail Compilation issues
ci/Performance-Testing fail build patch failure
ci/checkpatch success coding style OK

Commit Message

Lijun Ou April 19, 2021, 12:36 p.m. UTC
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.

Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
Signed-off-by: Lijun Ou <oulijun@huawei.com>
---
V3->V4:
- revert the V3 scheme.

V2->V3:
- The command implementation is changed so that the queuestate does
  not depend on the command execution.

V1->V2:
- use Tx instead of TX
- add note in doc
---
 app/test-pmd/cmdline.c                      | 84 +++++++++++++++++++++++++++++
 doc/guides/rel_notes/release_21_05.rst      |  2 +
 doc/guides/testpmd_app_ug/testpmd_funcs.rst | 11 ++++
 3 files changed, 97 insertions(+)

Comments

Ferruh Yigit April 19, 2021, 3:28 p.m. UTC | #1
On 4/19/2021 1:36 PM, 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)
> 

Instead of creating a new root level, 'tx_done_cleanup' command, what do you 
think to use existing port command, something like:

"port cleanup <port_id> txq <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.
> 
> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
> Signed-off-by: Lijun Ou <oulijun@huawei.com>
> ---
> V3->V4:
> - revert the V3 scheme.
> 
> V2->V3:
> - The command implementation is changed so that the queuestate does
>    not depend on the command execution.
> 
> V1->V2:
> - use Tx instead of TX
> - add note in doc
> ---
>   app/test-pmd/cmdline.c                      | 84 +++++++++++++++++++++++++++++
>   doc/guides/rel_notes/release_21_05.rst      |  2 +
>   doc/guides/testpmd_app_ug/testpmd_funcs.rst | 11 ++++
>   3 files changed, 97 insertions(+)
> 
> diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c
> index 5bf1497..b43964d 100644
> --- a/app/test-pmd/cmdline.c
> +++ b/app/test-pmd/cmdline.c
> @@ -675,6 +675,9 @@ 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"
> +

If 'free_cnt' is '0', driver should free all possible mbufs, can you add this 
detail to help?

>   			"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"
> @@ -16915,6 +16918,86 @@ 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;
> +	uint16_t port_id = res->port_id;
> +	uint16_t queue_id = res->queue_id;
> +	uint32_t free_cnt = res->free_cnt;
> +	struct rte_eth_txq_info qinfo;
> +	int ret;
> +
> +	if (rte_eth_tx_queue_info_get(port_id, queue_id, &qinfo)) {
> +		printf("Failed to get port %u Tx queue %u info!\n",
> +		       port_id, queue_id);
> +		return;
> +	}
> +
> +	if (qinfo.queue_state != RTE_ETH_QUEUE_STATE_STARTED) {
> +		printf("TX queue %u not started!\n", queue_id);
> +		return;
> +	}
> +
> +	/*
> +	 * 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.
> +	 */

Should there be a check to see if testpmd forwarding is stared or not?
This API shouldn't be allowed when forwarding is started.

> +	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 */
> @@ -17040,6 +17123,7 @@ 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 4538bb9..554499f 100644
> --- a/doc/guides/rel_notes/release_21_05.rst
> +++ b/doc/guides/rel_notes/release_21_05.rst
> @@ -217,6 +217,8 @@ New Features
>       ``show port (port_id) rxq (queue_id) desc used count``
>     * Added command to dump internal representation information of single flow.
>       ``flow dump (port_id) rule (rule_id)``
> +  * Added command to cleanup a Tx queue's mbuf on a port.
> +    ``tx_done_cleanup port <port_id> <queue_id> <free_cnt>``
>   
>   * **Updated ipsec-secgw sample application.**
>   
> diff --git a/doc/guides/testpmd_app_ug/testpmd_funcs.rst b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> index a736e7d..6472647 100644
> --- a/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> +++ b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> @@ -270,6 +270,17 @@ 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
>   ~~~~~~~~~~~
>   
>
Lijun Ou April 21, 2021, 1:44 a.m. UTC | #2
在 2021/4/19 23:28, Ferruh Yigit 写道:
> On 4/19/2021 1:36 PM, 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)
>>
> 
> Instead of creating a new root level, 'tx_done_cleanup' command, what do 
> you think to use existing port command, something like:
> 
> "port cleanup <port_id> txq <queue_id> <free_cnt>"
> 
Agree.
>> 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.
>>
>> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
>> Signed-off-by: Lijun Ou <oulijun@huawei.com>
>> ---
>> V3->V4:
>> - revert the V3 scheme.
>>
>> V2->V3:
>> - The command implementation is changed so that the queuestate does
>>    not depend on the command execution.
>>
>> V1->V2:
>> - use Tx instead of TX
>> - add note in doc
>> ---
>>   app/test-pmd/cmdline.c                      | 84 
>> +++++++++++++++++++++++++++++
>>   doc/guides/rel_notes/release_21_05.rst      |  2 +
>>   doc/guides/testpmd_app_ug/testpmd_funcs.rst | 11 ++++
>>   3 files changed, 97 insertions(+)
>>
>> diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c
>> index 5bf1497..b43964d 100644
>> --- a/app/test-pmd/cmdline.c
>> +++ b/app/test-pmd/cmdline.c
>> @@ -675,6 +675,9 @@ 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"
>> +
> 
> If 'free_cnt' is '0', driver should free all possible mbufs, can you add 
> this detail to help?
Agree. I will fix it.
> 
>>               "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"
>> @@ -16915,6 +16918,86 @@ 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;
>> +    uint16_t port_id = res->port_id;
>> +    uint16_t queue_id = res->queue_id;
>> +    uint32_t free_cnt = res->free_cnt;
>> +    struct rte_eth_txq_info qinfo;
>> +    int ret;
>> +
>> +    if (rte_eth_tx_queue_info_get(port_id, queue_id, &qinfo)) {
>> +        printf("Failed to get port %u Tx queue %u info!\n",
>> +               port_id, queue_id);
>> +        return;
>> +    }
>> +
>> +    if (qinfo.queue_state != RTE_ETH_QUEUE_STATE_STARTED) {
>> +        printf("TX queue %u not started!\n", queue_id);
>> +        return;
>> +    }
>> +
>> +    /*
>> +     * 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.
>> +     */
> 
> Should there be a check to see if testpmd forwarding is stared or not?
> This API shouldn't be allowed when forwarding is started.
> 
Yes. I will fix in the new version.
>> +    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 */
>> @@ -17040,6 +17123,7 @@ 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 4538bb9..554499f 100644
>> --- a/doc/guides/rel_notes/release_21_05.rst
>> +++ b/doc/guides/rel_notes/release_21_05.rst
>> @@ -217,6 +217,8 @@ New Features
>>       ``show port (port_id) rxq (queue_id) desc used count``
>>     * Added command to dump internal representation information of 
>> single flow.
>>       ``flow dump (port_id) rule (rule_id)``
>> +  * Added command to cleanup a Tx queue's mbuf on a port.
>> +    ``tx_done_cleanup port <port_id> <queue_id> <free_cnt>``
>>   * **Updated ipsec-secgw sample application.**
>> diff --git a/doc/guides/testpmd_app_ug/testpmd_funcs.rst 
>> b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
>> index a736e7d..6472647 100644
>> --- a/doc/guides/testpmd_app_ug/testpmd_funcs.rst
>> +++ b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
>> @@ -270,6 +270,17 @@ 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
>>   ~~~~~~~~~~~
>>
> 
> .
>
diff mbox series

Patch

diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c
index 5bf1497..b43964d 100644
--- a/app/test-pmd/cmdline.c
+++ b/app/test-pmd/cmdline.c
@@ -675,6 +675,9 @@  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"
@@ -16915,6 +16918,86 @@  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;
+	uint16_t port_id = res->port_id;
+	uint16_t queue_id = res->queue_id;
+	uint32_t free_cnt = res->free_cnt;
+	struct rte_eth_txq_info qinfo;
+	int ret;
+
+	if (rte_eth_tx_queue_info_get(port_id, queue_id, &qinfo)) {
+		printf("Failed to get port %u Tx queue %u info!\n",
+		       port_id, queue_id);
+		return;
+	}
+
+	if (qinfo.queue_state != RTE_ETH_QUEUE_STATE_STARTED) {
+		printf("TX queue %u not started!\n", queue_id);
+		return;
+	}
+
+	/*
+	 * 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 */
@@ -17040,6 +17123,7 @@  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 4538bb9..554499f 100644
--- a/doc/guides/rel_notes/release_21_05.rst
+++ b/doc/guides/rel_notes/release_21_05.rst
@@ -217,6 +217,8 @@  New Features
     ``show port (port_id) rxq (queue_id) desc used count``
   * Added command to dump internal representation information of single flow.
     ``flow dump (port_id) rule (rule_id)``
+  * Added command to cleanup a Tx queue's mbuf on a port.
+    ``tx_done_cleanup port <port_id> <queue_id> <free_cnt>``
 
 * **Updated ipsec-secgw sample application.**
 
diff --git a/doc/guides/testpmd_app_ug/testpmd_funcs.rst b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
index a736e7d..6472647 100644
--- a/doc/guides/testpmd_app_ug/testpmd_funcs.rst
+++ b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
@@ -270,6 +270,17 @@  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
 ~~~~~~~~~~~