[PATCH 0/3] testpmd support stop specify lcore

[PATCH 0/3] testpmd support stop specify lcore

[Chengwen Feng]

This patch support stop specify lcore for testpmd, and also include
two bugfix which found when test DCB function.

Chengwen Feng (3):
  app/testpmd: fix invalid txp when setup DCB forward
  app/testpmd: fix wrong Rx queues when setup DCB forward
  app/testpmd: support stop specify lcore

 app/test-pmd/cmdline.c                      | 63 +++++++++++++++++++++
 app/test-pmd/config.c                       |  9 +--
 doc/guides/testpmd_app_ug/testpmd_funcs.rst |  7 +++
 3 files changed, 73 insertions(+), 6 deletions(-)

-- 
2.17.1

[PATCH 1/3] app/testpmd: fix invalid txp when setup DCB forward

[Chengwen Feng]

The txp maybe invalid (e.g. start with only one port but set with 1),
this commit fix it by get txp from fwd_topology_tx_port_get() function.

An added benefit is that the DCB test also supports '--port-topology'
parameter.

Fixes: 1a572499beb6 ("app/testpmd: setup DCB forwarding based on traffic class")
Cc: stable@dpdk.org

Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
---
 app/test-pmd/config.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c
index 3ce2a14a1b..0f687018c7 100644
--- a/app/test-pmd/config.c
+++ b/app/test-pmd/config.c
@@ -5187,7 +5187,7 @@ dcb_fwd_config_setup(void)
 	/* reinitialize forwarding streams */
 	init_fwd_streams();
 	sm_id = 0;
-	txp = 1;
+	txp = fwd_topology_tx_port_get(rxp);
 	/* get the dcb info on the first RX and TX ports */
 	(void)rte_eth_dev_get_dcb_info(fwd_ports_ids[rxp], &rxp_dcb_info);
 	(void)rte_eth_dev_get_dcb_info(fwd_ports_ids[txp], &txp_dcb_info);
@@ -5235,11 +5235,8 @@ dcb_fwd_config_setup(void)
 			rxp++;
 		if (rxp >= nb_fwd_ports)
 			return;
+		txp = fwd_topology_tx_port_get(rxp);
 		/* get the dcb information on next RX and TX ports */
-		if ((rxp & 0x1) == 0)
-			txp = (portid_t) (rxp + 1);
-		else
-			txp = (portid_t) (rxp - 1);
 		rte_eth_dev_get_dcb_info(fwd_ports_ids[rxp], &rxp_dcb_info);
 		rte_eth_dev_get_dcb_info(fwd_ports_ids[txp], &txp_dcb_info);
 	}
-- 
2.17.1

[PATCH 2/3] app/testpmd: fix wrong Rx queues when setup DCB forward

[Chengwen Feng]

The nb_rx_queue should get from rxp_dcb_info not txp_dcb_info, this
commit fix it.

Fixes: 1a572499beb6 ("app/testpmd: setup DCB forwarding based on traffic class")
Cc: stable@dpdk.org

Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
---
 app/test-pmd/config.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c
index 0f687018c7..8557371488 100644
--- a/app/test-pmd/config.c
+++ b/app/test-pmd/config.c
@@ -5205,7 +5205,7 @@ dcb_fwd_config_setup(void)
 				fwd_lcores[lc_id]->stream_idx;
 			rxq = rxp_dcb_info.tc_queue.tc_rxq[i][tc].base;
 			txq = txp_dcb_info.tc_queue.tc_txq[i][tc].base;
-			nb_rx_queue = txp_dcb_info.tc_queue.tc_rxq[i][tc].nb_queue;
+			nb_rx_queue = rxp_dcb_info.tc_queue.tc_rxq[i][tc].nb_queue;
 			nb_tx_queue = txp_dcb_info.tc_queue.tc_txq[i][tc].nb_queue;
 			for (j = 0; j < nb_rx_queue; j++) {
 				struct fwd_stream *fs;
-- 
2.17.1

[PATCH 3/3] app/testpmd: support stop specify lcore

[Chengwen Feng]

This commit supports stop specify lcore, the command:

  stop fwd_core (lcore_id)

The background of this command:
1. Only some TCs are expected to generate traffic when the DCB function
   is tested based on txonly forwarding.
2. Because each lcore will process all the traffic of one TC, therefore,
   we could stop the lcores which process unexpected TCs by this
   command.

Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
---
 app/test-pmd/cmdline.c                      | 63 +++++++++++++++++++++
 doc/guides/testpmd_app_ug/testpmd_funcs.rst |  7 +++
 2 files changed, 70 insertions(+)

diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c
index 22afbdbad3..e03f6e6181 100644
--- a/app/test-pmd/cmdline.c
+++ b/app/test-pmd/cmdline.c
@@ -150,6 +150,9 @@ static void cmd_help_long_parsed(void *parsed_result,
 			"    Stop packet forwarding, and display accumulated"
 			" statistics.\n\n"
 
+			"stop fwd_core (lcore_id)\n"
+			"    Stop specify lcore's forwarding.\n\n"
+
 			"quit\n"
 			"    Quit to prompt.\n\n"
 		);
@@ -3975,6 +3978,65 @@ static cmdline_parse_inst_t cmd_stop = {
 	},
 };
 
+/* *** stop specify forward core *** */
+struct cmd_stop_fwd_core_result {
+	cmdline_fixed_string_t stop;
+	cmdline_fixed_string_t fwd_core;
+	uint32_t lcore_id;
+};
+
+static void
+cmd_stop_fwd_core_parsed(void *parsed_result,
+			 __rte_unused struct cmdline *cl,
+			 __rte_unused void *data)
+{
+	struct cmd_stop_fwd_core_result *res = parsed_result;
+	struct fwd_lcore *fc = lcore_to_fwd_lcore(res->lcore_id);
+
+	if (test_done) {
+		fprintf(stderr, "Packet forwarding not started\n");
+		return;
+	}
+
+	if (fc == NULL) {
+		fprintf(stderr, "core: %u not in the forward corelist.\n", res->lcore_id);
+		return;
+	}
+
+	if (fc->stopped) {
+		fprintf(stderr, "core: %u already stopped!\n", res->lcore_id);
+		return;
+	}
+
+	printf("Telling core: %u to stop...", res->lcore_id);
+	fc->stopped = 1;
+	printf("\nWaiting for core: %u to finish...\n", res->lcore_id);
+	rte_eal_wait_lcore(res->lcore_id);
+	printf("Done.\n");
+}
+
+static cmdline_parse_token_string_t cmd_stop_fwd_core_stop =
+	TOKEN_STRING_INITIALIZER(struct cmd_stop_fwd_core_result,
+			stop, "stop");
+static cmdline_parse_token_string_t cmd_stop_fwd_core_fwd_core =
+	TOKEN_STRING_INITIALIZER(struct cmd_stop_fwd_core_result,
+			fwd_core, "fwd_core");
+static cmdline_parse_token_num_t cmd_stop_fwd_core_lcore_id =
+	TOKEN_NUM_INITIALIZER(struct cmd_stop_fwd_core_result,
+			lcore_id, RTE_UINT32);
+
+static cmdline_parse_inst_t cmd_stop_fwd_core = {
+	.f = cmd_stop_fwd_core_parsed,
+	.data = NULL,
+	.help_str = "stop fwd_core <lcore_id>: stop specify lcore's forwarding.",
+	.tokens = {
+		(void *)&cmd_stop_fwd_core_stop,
+		(void *)&cmd_stop_fwd_core_fwd_core,
+		(void *)&cmd_stop_fwd_core_lcore_id,
+		NULL,
+	},
+};
+
 static unsigned int
 get_ptype(char *value)
 {
@@ -14051,6 +14113,7 @@ static cmdline_parse_ctx_t builtin_ctx[] = {
 	&cmd_config_dcb,
 	&cmd_read_rxd_txd,
 	&cmd_stop,
+	&cmd_stop_fwd_core,
 	&cmd_mac_addr,
 	&cmd_set_fwd_eth_peer,
 	&cmd_set_xstats_hide_zero,
diff --git a/doc/guides/testpmd_app_ug/testpmd_funcs.rst b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
index e423abd40e..0a362d06b8 100644
--- a/doc/guides/testpmd_app_ug/testpmd_funcs.rst
+++ b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
@@ -143,6 +143,13 @@ Stop packet forwarding, and display accumulated statistics::
 
    testpmd> stop
 
+stop fwd_core
+~~~~~~~~~~~~~
+
+Stop specify lcore's forwarding::
+
+   testpmd> stop fwd_core (lcore_id)
+
 quit
 ~~~~
 
-- 
2.17.1

Re: [PATCH 0/3] testpmd support stop specify lcore

[Stephen Hemminger]

On Tue, 4 Nov 2025 12:09:13 +0800
Chengwen Feng <fengchengwen@huawei.com> wrote:

> This patch support stop specify lcore for testpmd, and also include
> two bugfix which found when test DCB function.
> 
> Chengwen Feng (3):
>   app/testpmd: fix invalid txp when setup DCB forward
>   app/testpmd: fix wrong Rx queues when setup DCB forward
>   app/testpmd: support stop specify lcore
> 
>  app/test-pmd/cmdline.c                      | 63 +++++++++++++++++++++
>  app/test-pmd/config.c                       |  9 +--
>  doc/guides/testpmd_app_ug/testpmd_funcs.rst |  7 +++
>  3 files changed, 73 insertions(+), 6 deletions(-)
> 

If there is a stop lcore, why is there not a command to restart the lcore?
Looks like this just an optimization for DCB.
Could it be handled better by having testpmd not spawn lcores that
have no queues? 

Re: [PATCH 0/3] testpmd support stop specify lcore

[fengchengwen]

On 11/5/2025 8:21 AM, Stephen Hemminger wrote:
> On Tue, 4 Nov 2025 12:09:13 +0800
> Chengwen Feng <fengchengwen@huawei.com> wrote:
> 
>> This patch support stop specify lcore for testpmd, and also include
>> two bugfix which found when test DCB function.
>>
>> Chengwen Feng (3):
>>   app/testpmd: fix invalid txp when setup DCB forward
>>   app/testpmd: fix wrong Rx queues when setup DCB forward
>>   app/testpmd: support stop specify lcore
>>
>>  app/test-pmd/cmdline.c                      | 63 +++++++++++++++++++++
>>  app/test-pmd/config.c                       |  9 +--
>>  doc/guides/testpmd_app_ug/testpmd_funcs.rst |  7 +++
>>  3 files changed, 73 insertions(+), 6 deletions(-)
>>
> 
> If there is a stop lcore, why is there not a command to restart the lcore?

The restart lcore is more complex which include data prepare (init).

But I think could impl such pause / restart function by config fc->stopped a special value:

Current:
	run_pkt_fwd_on_lcore(struct fwd_lcore *fc, packet_fwd_t pkt_fwd)
	{
		do {
			forwarding logic
		} while(!fc->stopped);
	}

We could adjust the logic to support pause / restart function:
	run_pkt_fwd_on_lcore(struct fwd_lcore *fc, packet_fwd_t pkt_fwd)
	{
	_restart:
		do {
			forwarding logic
		} while(!fc->stopped);
 		while (fc->stopped == 2) {
			nop
		}
		if (fc->stopped == 1)
			return;
		if (fc->stopped == 0)
			// means restart
			goto _restart;
	}
So we could configure fc->stopped = 2 to pause forwarding, and config it to 0 to restart forwarding.

> Looks like this just an optimization for DCB.

Yes, mainly for test the Tx direction's DCB function.

> Could it be handled better by having testpmd not spawn lcores that
> have no queues? 

The lcore spawned by testpmd always has queues. In this patchset, we just stop some queue's forwarding.

>