netdev - Re: [PATCH net-next v3 0/2] socket statistics for ss

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Message-ID: <ba77dfc0-56fe-9c1c-f68d-e8c06ffa1cb4@gmail.com>
Date:   Wed, 9 May 2018 11:53:50 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Stephen Hemminger <stephen@...workplumber.org>,
        Eric Dumazet <eric.dumazet@...il.com>
Cc:     davem@...emloft.net, gerrit@....abdn.ac.uk, kuznet@....inr.ac.ru,
        yoshfuji@...ux-ipv6.org, netdev@...r.kernel.org,
        dccp@...r.kernel.org, Stephen Hemminger <sthemmin@...rosoft.com>
Subject: Re: [PATCH net-next v3 0/2] socket statistics for ss



On 05/09/2018 11:44 AM, Stephen Hemminger wrote:
> On Wed, 9 May 2018 10:53:58 -0700
> Eric Dumazet <eric.dumazet@...il.com> wrote:
> 
>> On 05/09/2018 10:31 AM, Stephen Hemminger wrote:
>>> On Wed, 9 May 2018 10:18:23 -0700
>>> Eric Dumazet <eric.dumazet@...il.com> wrote:
>>>   
>>>> On 05/09/2018 08:22 AM, Stephen Hemminger wrote:
>>>>  
>>>>> I am not sure if these patches are worth applying.
>>>>> The 'ss -s' command has had missing values since 2.4 kernel.
>>>>> And the first complaints came in only this year.
>>>>>
>>>>> Another alternative would be just to remove these fields from ss -s
>>>>> output and move on.
>>>>>     
>>>>
>>>> Anyway your patches are not netns ready, so lets remove these fields from ss.
>>>>
>>>> Or you have to spend _much_ more time on writing and testing the kernel part.
>>>>
>>>> Thanks.  
>>>
>>> The patches only expose the existing TCP socket accounting infrastructure.
>>> Several other pieces that sockstat has are not netns aware.
>>> That is a completely different problem.  
>>
>>
>> Adding a new field counting 'bounds ports' without being netns ready is a total mistake,
>> as it is useless by current standards.
>>
>> The first thing that users will do is add proper netns support, with extra complexity in the kernel.
>>
>> So, instead of pushing some incomplete feature, trying to fool ourselves with a sentiment of 'small cost'
>> that will later need another 100 lines of code in the kernel, please give us the complete picture.
>>
>> I am just saying, you can of course ignore my feedback.
> 
> The current TCP hashinfo should be moved into netns. The current method of scanning and matching
> by net namespace is a scalability issue now.

It is not the plan yet, and we have no scalability issue.

Before switching to netns hash table, this would need rhashtable conversions
but so far this has not been done.

- Time to create/delete netns is critical.
- Adding few Mbytes of overhead per netns is a nogo,

Please do not change subject, this is adding noise to this particular thread.