Re: [dpdk-dev] [PATCH V2 1/7] app/testpmd: fix forward lcores number when DCB test

["Li, Xiaoyun" <xiaoyun.li@intel.com>]

> -----Original Message-----
> From: Huisong Li <lihuisong@huawei.com>
> Sent: Tuesday, April 20, 2021 15:32
> To: dev@dpdk.org
> Cc: Yigit, Ferruh <ferruh.yigit@intel.com>; Li, Xiaoyun <xiaoyun.li@intel.com>;
> linuxarm@openeuler.org; lihuisong@huawei.com
> Subject: [PATCH V2 1/7] app/testpmd: fix forward lcores number when DCB test
> 
> Currently, 'nb_fwd_lcores' value are both adjusted based on 'nb_fwd_streams' in
> rss/simple/icmp_echo_fwd_config_setup.
> But the operation is missing in dcb_fwd_config_setup, which may lead to a bad
> behavior in which multiple polling threads operate on the same queue. 

This patch is OK. But commit log is redundant and confusing.
The above is enough to explain what your patch is doing and can even be more simple.

>In this
> case, the device sends and receives packets, causing unexpected results. The
> procedure is  as follows:

I don't understand what you're saying here. The commands you're showing is 8 nbcores dealing with 16 queues. So it's one thread dealing with multiple queues which doesn't have issues at all.
Please remove the useless and confusing commands.

> 1/ run testpmd with "--rxq=8 --txq=8"
> 2/ port stop all
> 3/ set nbcore 8
> 4/ port config 0 dcb vt off 4 pfc on
> 5/ port config all rxq 16
> 6/ port config all txq 16
> 7/ port start all
> 8/ set fwd mac
> 9/ start
> 
> For the DCB forwarding test, each core is assigned to each traffic class and each
> core is assigned a multi-stream.
> Therefore, 'nb_fwd_lcores' value needs to be adjusted based  on 'total_tc_num'
> in all forwarding ports.

Please refer to the RSS fwd config fix patch to write your own commit log. Use simple and easy-understanding words to explain yourself.
Below is the reference of RSS.

commit 017d680a91fcf30da14a6d3a2f96d41f6dda3a0f
Author: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Date:   Mon Jun 27 23:35:19 2016 +0100

    app/testpmd: limit number of forwarding cores

    Number of forwarding cores must be equal or less than
    number of forwarding streams, otherwise two cores
    would try to use a same queue on a port, which is not allowed.

> 
> Fixes: 900550de04a7 ("app/testpmd: add dcb support")
> Fixes: ce8d561418d4 ("app/testpmd: add port configuration settings")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Huisong Li <lihuisong@huawei.com>
> Signed-off-by: Lijun Ou <oulijun@huawei.com>
> ---
>  app/test-pmd/config.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c index
> ccb9bd3..03ee40c 100644
> --- a/app/test-pmd/config.c
> +++ b/app/test-pmd/config.c
> @@ -2961,6 +2961,21 @@ rss_fwd_config_setup(void)
>  	}
>  }
> 
> +static uint16_t
> +get_fwd_port_total_tc_num(void)
> +{
> +	struct rte_eth_dcb_info dcb_info;
> +	uint16_t total_tc_num = 0;
> +	unsigned int i;
> +
> +	for (i = 0; i < nb_fwd_ports; i++) {
> +		(void)rte_eth_dev_get_dcb_info(fwd_ports_ids[i], &dcb_info);
> +		total_tc_num += dcb_info.nb_tcs;
> +	}
> +
> +	return total_tc_num;
> +}
> +
>  /**
>   * For the DCB forwarding test, each core is assigned on each traffic class.
>   *
> @@ -2980,12 +2995,16 @@ dcb_fwd_config_setup(void)
>  	lcoreid_t  lc_id;
>  	uint16_t nb_rx_queue, nb_tx_queue;
>  	uint16_t i, j, k, sm_id = 0;
> +	uint16_t total_tc_num;
>  	uint8_t tc = 0;
> 
>  	cur_fwd_config.nb_fwd_lcores = (lcoreid_t) nb_fwd_lcores;
>  	cur_fwd_config.nb_fwd_ports = nb_fwd_ports;
>  	cur_fwd_config.nb_fwd_streams =
>  		(streamid_t) (nb_rxq * cur_fwd_config.nb_fwd_ports);
> +	total_tc_num = get_fwd_port_total_tc_num();
> +	if (cur_fwd_config.nb_fwd_lcores > total_tc_num)
> +		cur_fwd_config.nb_fwd_lcores = total_tc_num;
> 
>  	/* reinitialize forwarding streams */
>  	init_fwd_streams();
> --
> 2.7.4