Re: [dpdk-dev] [PATCH 2/3] app/testpmd: remove forwarding config from parsing Rx and Tx

[oulijun <oulijun@huawei.com>]

在 2021/3/24 9:44, Li, Xiaoyun 写道:
> 
> 
>> -----Original Message-----
>> From: oulijun <oulijun@huawei.com>
>> Sent: Wednesday, March 24, 2021 09:01
>> To: Li, Xiaoyun <xiaoyun.li@intel.com>; Yigit, Ferruh <ferruh.yigit@intel.com>
>> Cc: dev@dpdk.org; linuxarm@openeuler.org
>> Subject: Re: [PATCH 2/3] app/testpmd: remove forwarding config from parsing
>> Rx and Tx
>>
>>
>>
>> 在 2021/3/23 15:50, 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 2/3] app/testpmd: remove forwarding config from
>>>> parsing Rx and Tx
>>>>
>>>> From: Huisong Li <lihuisong@huawei.com>
>>>>
>>>
>>> The commit message should be more simple and avoids grammar mistakes.
>>>
>> All right, I will simply it.
>>>> The "fwd_config_setup()" function does release and apply for memory
>>>> of forwarding flows, and re-establish these streams when rxq/txq or
>>>> rxd/txd is changed. The function is also called by
>>>> "start_packet_forwarding()" when user executes "start" cmd.
>>>> All changes for rxq/txq or rxd/txd can be updated uniformly when this
>>>> command is executed. Therefore, it is a little redundant in the
>> "cmd_config_rx_tx_parsed"
>>>> function.
>>>
>>> It's not redundant. This command may configure number of rxq/txq. So the
>> fwd streams map may change.
>>> Then it's common to check the fwd streams after this command using "show
>> config fwd".
>>> If you remove this fwd stream update, users can't get the correct new fwd
>> streams until they start the traffic.
>>> But they may change a lot of things and want to check if the setting is correct
>> before they start the traffic.
>>>
>> Yes, you are right. It's really unfriendly.
>>>>
>>>> In addition, the forwarding stream under one TC is configured based
>>>> on number of queues allocated to TC. And number of queues allocated
>>>> to TC is updated after calling  "rte_eth_dev_configure"
>>>> again. If the number of queues is reduced after configuring the DCB,
>>>> and then, release and apply for stream memory, and reinitialize the
>>>> forwarding stream under the DCB mode based on the old TC information.
>>>> As a result, null pointer may be accessed.
>>>
>>> I think you should add "rte_eth_dev_configure " into dcb_fwd_config_setup()
>> before rte_eth_dev_get_dcb_info().
>>>
>>> And the commit message should be similar like the following:
>>> Segment fault might happen after configuring queue number to less because
>> dcb_fwd_config_setup setup dcb based on old dcb info.
>>> And dcb info can only update after rte_eth_dev_configure().
>>> So this patch adds rte_eth_dev_configure() before rte_eth_dev_get_dcb_info()
>> to get updated dcb info to fix this issue.
>>>
>> Thank you for your advice. But the above adjustments may still not work for
>> some drivers. The mapping between queues and TCs in these drivers is updated
>> in the dev_start stage.
>>
>> I have an idea. We can move fwd_config_setup() to start_port(), which is called
>> by main() and after starting ports This not only solves the segment fault, but also
>> does not have the problem you mentioned above. I test it and it is ok.
>>
>> What do you think, xiaoyun?
> 
> How can you fix the issue I mentioned?
> You still need to start port first to see the updated fwd config.
Yes. But it can make sure that users get the correct new fwd streams  
before executing the 'start' command.
> And for those drivers, why does the mapping has to be updated in dev_start stage?
> What does it need? Can't it be moved to dev_configure?
The framework does not require that the configuration parameters  
transferred by the dev_configure API must
be updated in the interface of driver. The driver can  verify the  
correctness of these parameters in the interface,
and then complete the update in the dev_start stage. It depends on the  
design and need of the driver. Maybe
it's more appropriate to put it in dev_configure, but now we can't ask  
all these drivers to modify the operation.
>>
>>
>>>>
>>>> Like:
>>>> set nbcore 4
>>>> port stop all
>>>> port config 0 dcb vt off 4 pfc on
>>>> port start all
>>>> port stop all
>>>> port config all rxq 8
>>>> port config all txq 8
>>>>
>>>> At the moment, a segmentation fault occurs.
>>>>
>>>> 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>
>>>> ---
>>>> V1->V2:
>>>> - use stream instead of flow
>>>> ---
>>>>    app/test-pmd/cmdline.c | 2 --
>>>>    1 file changed, 2 deletions(-)
>>>>
>>>> diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c index
>>>> 4df0c32..e316f5c 100644
>>>> --- a/app/test-pmd/cmdline.c
>>>> +++ b/app/test-pmd/cmdline.c
>>>> @@ -1837,8 +1837,6 @@ cmd_config_rx_tx_parsed(void *parsed_result,
>>>>    		return;
>>>>    	}
>>>>
>>>> -	fwd_config_setup();
>>>> -
>>>>    	init_port_config();
>>>>
>>>>    	cmd_reconfig_device_queue(RTE_PORT_ALL, 1, 1);
>>>> --
>>>> 2.7.4
>>>
>>> .
>>>
> .
>