[dpdk-stable] [dpdk-dev] [PATCH v2 1/1] fbarray: get fbarrays from containerized secondary

[Burakov, Anatoly]

On 11-Jul-19 10:37 AM, Yasufumi Ogawa wrote:
> On 2019/07/09 19:26, Burakov, Anatoly wrote:
>> On 09-Jul-19 11:24 AM, Burakov, Anatoly wrote:
>>> On 09-Jul-19 11:22 AM, Yasufumi Ogawa wrote:
>>>> Hi Anatoly,
>>>>
>>>> On 2019/07/05 17:53, Burakov, Anatoly wrote:
>>>>> On 16-Apr-19 4:43 AM, ogawa.yasufumi at lab.ntt.co.jp wrote:
>>>>>> From: Yasufumi Ogawa <ogawa.yasufumi at lab.ntt.co.jp>
>>>>>>
>>>>>> In secondary_msl_create_walk(), it creates a file for fbarrays 
>>>>>> with its
>>>>>> PID for reserving unique name among secondary processes. However, it
>>>>>> does not work if secondary is run as app container because each of
>>>>>> containerized secondary has PID 1. To reserve unique name, use 
>>>>>> hostname
>>>>>> instead of PID if the value is 1.
>>>>>>
>>>>>> Cc: stable at dpdk.org
>>>>>>
>>>>>> Signed-off-by: Yasufumi Ogawa <ogawa.yasufumi at lab.ntt.co.jp>
>>>>>> ---
>>>>>
>>>>> I'm not too well versed in containers - is this hostname 1) always 
>>>>> set, and 2) always unique?
>>>> For docker, 1) hostname is always set. 2) The hostname is decided as 
>>>> short form of container ID, so it might not be unique even though 
>>>> very low possibility.
>>>>
>>>> I found that we can get whole container ID in `/proc/self/cgroup` as 
>>>> discussed [1]. I think using hostname is reasonable way without 
>>>> running many secondary processes. However, it might be better to use 
>>>> 64 digits full container ID instead of 12 digits short ID if ensure 
>>>> uniqueness strongly. What do yo think?
>>>>
>>>> [1] 
>>>> https://forums.docker.com/t/get-a-containers-full-id-from-inside-of-itself/37237 
>>>>
>>>
>>> I think it's better to err on the side of caution and guarantee 
>>> better uniqueness. This code will get into an LTS and will be used 
>>> for years to come :)
>>>
>>
>> ...however, i think a full 64-digit ID won't even fit into the fbarray 
>> filename, as i believe it's limited to something like 64 chars. 
>> Perhaps hostname would be enough after all... or we can increase 
>> fbarray name length - that would require ABI breakage but the ABI is 
>> already broken in this release, so it's OK i think.
> OK.

Just a note: you're targetting this fix towards stable too. For stable, 
you cannot break ABI, so we would have to do with the shorter hostname. 
It's only for 19.08 that you can change fbarray length and use the full 
64-char container ID for uniqueness.

> 
>  >> Wouldn't an error in fscanf() leak the file handle? I think you need 
> to fclose() before checking the result.
>  > I would like to fix it.
> I would like send v3 patch for fixing for fclose().

Please do :)

> 
> Thanks,
> Yasufumi
> 
> 


-- 
Thanks,
Anatoly