Re: [dpdk-dev] [PATCH 1/3] app/testpmd: fix forwarding configuration when DCB test

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

On 3/23/2021 2:17 PM, oulijun wrote:
> 
> 
> 在 2021/3/23 16:55, Li, Xiaoyun 写道:
>> Hi
>>
>>> -----Original Message-----
>>> From: Lijun Ou <oulijun@huawei.com>
>>> Sent: Friday, March 5, 2021 18:22
>>> To: Yigit, Ferruh <ferruh.yigit@intel.com>
>>> Cc: Li, Xiaoyun <xiaoyun.li@intel.com>; dev@dpdk.org;
>>> linuxarm@openeuler.org
>>> Subject: [PATCH 1/3] app/testpmd: fix forwarding configuration when DCB test
>>>
>>> From: Huisong Li <lihuisong@huawei.com>
>>>
>> The commit message is too long and redundant. Please simplify it.
>>
>>> 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 lack for
>>> dcb_fwd_config_setup, which may lead to a bad events where multiple polling
>>> threads operate on the same queue. As a result, various possible exceptions will
>>> occur. The procedure is as follows:
>>>
>>> startup testpmd app as follows:
>>> testpmd> port stop all
>>> testpmd> set nbcore 8
>>> testpmd> port config 0 dcb vt off 4 pfc on port config all rxq 16 port
>>> testpmd> config all txq 16 port start all set fwd mac
>>> Logical Core 1 (socket 0) forwards packets on 4 streams:
>>> RX P=0/Q=0 (socket 0) -> TX P=0/Q=0 (socket 0) peer=02:00:00:00:00:00 RX
>>> P=0/Q=1 (socket 0) -> TX P=0/Q=1 (socket 0) peer=02:00:00:00:00:00 RX
>>> P=0/Q=2 (socket 0) -> TX P=0/Q=2 (socket 0) peer=02:00:00:00:00:00 RX
>>> P=0/Q=3 (socket 0) -> TX P=0/Q=3 (socket 0) peer=02:00:00:00:00:00 Logical
>>> Core 2 (socket 0) forwards packets on 4 streams:
>>> RX P=0/Q=4 (socket 0) -> TX P=0/Q=4 (socket 0) peer=02:00:00:00:00:00 RX
>>> P=0/Q=5 (socket 0) -> TX P=0/Q=5 (socket 0) peer=02:00:00:00:00:00 RX
>>> P=0/Q=6 (socket 0) -> TX P=0/Q=6 (socket 0) peer=02:00:00:00:00:00 RX
>>> P=0/Q=7 (socket 0) -> TX P=0/Q=7 (socket 0) peer=02:00:00:00:00:00 Logical
>>> Core 3 (socket 0) forwards packets on 4 streams:
>>> RX P=0/Q=8 (socket 0) -> TX P=0/Q=8 (socket 0) peer=02:00:00:00:00:00 RX
>>> P=0/Q=9 (socket 0) -> TX P=0/Q=9 (socket 0) peer=02:00:00:00:00:00 RX
>>> P=0/Q=10 (socket 0) -> TX P=0/Q=10 (socket 0) peer=02:00:00:00:00:00 RX
>>> P=0/Q=11 (socket 0) -> TX P=0/Q=11 (socket 0) peer=02:00:00:00:00:00 Logical
>>> Core 4 (socket 0) forwards packets on 4 streams:
>>> RX P=0/Q=12 (socket 0) -> TX P=0/Q=12 (socket 0) peer=02:00:00:00:00:00 RX
>>> P=0/Q=13 (socket 0) -> TX P=0/Q=13 (socket 0) peer=02:00:00:00:00:00 RX
>>> P=0/Q=14 (socket 0) -> TX P=0/Q=14 (socket 0) peer=02:00:00:00:00:00 RX
>>> P=0/Q=15 (socket 0) -> TX P=0/Q=15 (socket 0) peer=02:00:00:00:00:00 Logical
>>> Core 5 (socket 0) forwards packets on 1 streams:
>>> RX P=0/Q=4 (socket 0) -> TX P=0/Q=4 (socket 0) peer=02:00:00:00:00:00 Logical
>>> Core 6 (socket 0) forwards packets on 1 streams:
>>> RX P=0/Q=5 (socket 0) -> TX P=0/Q=5 (socket 0) peer=02:00:00:00:00:00 Logical
>>> Core 7 (socket 0) forwards packets on 1 streams:
>>> RX P=0/Q=6 (socket 0) -> TX P=0/Q=6 (socket 0) peer=02:00:00:00:00:00 Logical
>>> Core 8 (socket 0) forwards packets on 1 streams:
>>> RX P=0/Q=7 (socket 0) -> TX P=0/Q=7 (socket 0) peer=02:00:00:00:00:00
>>>
>>> Notice: number of rxq and txq in running cmdline are greater than used nb_tc.
>>>
>>> For the DCB forwarding test, each core is assigned on each traffic class and 
>>> each
>>> core is assigned a multi-stream. Therefore, 'nb_fwd_lcores'
>>> value can be adjusted based on 'total_tc_num' in all forwarding ports.
>>>
>>> In addition, after operation of port stop/port start, forwarding 
>>> configuration is
>>> changed by rss_fwd_config_setup. In "start_port"
>>> function, dcb_test is set to 1 based on dcb_config. So it also should be cleared
>>> when dcb_config is 0.
>>>
>>> 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 +++++++++++++++++++  app/test-pmd/testpmd.c |
>>> 12 +++++++-----
>>>   2 files changed, 26 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c index
>>> 576d5ac..c89f8cd 100644
>>> --- a/app/test-pmd/config.c
>>> +++ b/app/test-pmd/config.c
>>> @@ -2864,6 +2864,21 @@ 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;
>>> +}
>>
>> It's only 3 lines. Is it really necessary to make it into a function which is 
>> not called by anyone else? A comment and the loop are enough.
>>
> To calculate the total number of TCs on all forwarding ports, we have to call  
> rte_eth_dev_get_dcb_info().  However,  rte_eth_dev_get_dcb_info()
> has been called twice by dcb_fwd_config_setup() to setup dcb forwarding 
> configuration. The dcb_fwd_config_setup() might be more readable
> if encapsulated, I think.  In addition, variables in "cur_fwd_config" are 
> initialized more centrally. What do you think?

+1 to have the function, agree it makes more readable.

But for the PMDs that doesn't support '.get_dcb_info' it will return 0, causing 
'nb_fwd_lcores' to be zero, I think this should be prevented.
Either can add a zero check here, or do the check during "port config # dcb ..." 
and prevent setting 'dcb_config' at first place for those pmds. I think second 
option is better, what do you think.

Overall DCB support in the testpmd seems missing some corner cases and requires 
more update/fix.

>>> +
>>>   /**
>>>    * For the DCB forwarding test, each core is assigned on each traffic class.
>>>    *
>>> @@ -2883,12 +2898,16 @@ 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 = 0;
>>>       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();
>>> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c index
>>> 1a57324..7eb810b 100644
>>> --- a/app/test-pmd/testpmd.c
>>> +++ b/app/test-pmd/testpmd.c
>>> @@ -2707,14 +2707,16 @@ stop_port(portid_t pid)
>>>       portid_t peer_pl[RTE_MAX_ETHPORTS];
>>>       int peer_pi;
>>>
>>> -    if (dcb_test) {
>>> -        dcb_test = 0;
>>> -        dcb_config = 0;
>>> -    }
>>> -
>>>       if (port_id_is_invalid(pid, ENABLED_WARN))
>>>           return;
>>>
>>> +    /*
>>> +     * In "start_port" function, dcb_test is set to 1 based on dcb_config.
>>> +     * So it should be cleared when dcb_config is 0.
>>> +     */
>>> +    if (dcb_config == 0)
>>> +        dcb_test = 0;
>>> +
>>
>> I don't understand why are you changing this.
>> dcb_test will only be set when dcb_config is 1 when starting ports. And both 
>> dcb_test and dcb_config will be cleared when stopping ports.
>> So dcb will only affect when you set port dcb and then start port and when 
>> stop port dcb will be cleared.
>>
>> So what's the problem of original codes?
>>
>> Your change will cause issues that there's no place to set dcb_config as 0. If 
>> you config dcb, then it'll be always dcb mode unless restart the whole testpmd.
>>
>>>       printf("Stopping ports...\n");
>>>
>>>       RTE_ETH_FOREACH_DEV(pi) {
>>> -- 
>>> 2.7.4
>>
>> .
>>