[dpdk-stable] [dpdk-dev] [PATCH] app/testpmd: don't allow to dynamic change nbcore

[Ferruh Yigit]

On 10/29/2020 4:43 AM, Dharmik Thakkar wrote:

<...>

>> On Oct 27, 2020, at 1:42 AM, Zhou Zhenghua <zhenghuax.zhou at intel.com> wrote:
>>
>> When changing the number of forwarding cores in runtime, two issues may be
>> encountered:
>>
>>   - If the setting nbcore little than current nbcore, the forwarding
>>     thread will still running on the extra cores. Therefore, trying to
>>     stop forwarding will hang testpmd, since it will wait for the extra
>>     cores to stop.
>>
>>   - If the setting nbcore greate than actual nbcore, the newly added
>>     cores are not allocated resources.
>>
>> This will face the problem of dynamic resource allocation, so it's not
>> allow to changes nbcore number when forwarding is running.
>>
>> Fixes: 0c0db76f42ed ("app/testpmd: separate forward config setup from display")
>> Cc: bernard.iremonger at intel.com
>> Cc: stable at dpdk.org
>>
>> Signed-off-by: Zhou Zhenghua <zhenghuax.zhou at intel.com>
> 
 > Hi Zhou,
 >
 > Although, I see that a few of the configuration options are checking for 
’test_done’, I am wondering if it is truly required.
 > Since, as per the documentation guidelines:
 > 'Configuration changes only become active when forwarding is started/restarted.’
 >
Yes documentation has it and I think that is what happens in below bullet 2 
(increase core count).

But it is easy to reproduce the hung mentioned in the first bullet, I am for 
having this fix.
And this won't contradict with the above document, the config options you can 
set will be taken account when forwarding is started/restarted, but this one 
won't be set because of added check, hence:
Acked-by: Ferruh Yigit <ferruh.yigit at intel.com>

@Zhou,
do you have any objection to remove bullet 2 while merging?