Re: [PATCH v2 1/2] perf: add container identifier entry in perf sample data

[Hari Bathini <hbathini@linux.vnet.ibm.com>]

On Friday 02 September 2016 07:29 PM, Peter Zijlstra wrote:
> On Fri, Sep 02, 2016 at 07:25:31PM +0530, Hari Bathini wrote:
>>> I'm thinking this value is mostly the same for tasks, just like COMM and
>> I think so, too. Namespaces aren't changed that often for tasks...
>>
>>> MMAP. Could we therefore not emit (sideband) events whenever a task
>>> changes namespace and get the same information but with tons less data?
>> You mean, something like PERF_RECORD_NAMESPACE that
>> emits events on fork, clone, setns..?
> Yep.

Ok. Thanks!

>
>>> That also gives the possibility of recording all namespaces, not just
>>> the one.
>> True. If we record all namespaces, container identifier interpretation
>> can be left to the userspace to decide, which is much more flexible...
> The only complication is initial state, on record start you'd have to
> trawl /proc and generate 'fake' namespace records for all (relevant)
> tasks.
>
> We do the same with MMAP records, we parse /proc/$pid/maps for that.
>
> Is this namespace stuff available in /proc somewhere?
>

Yes, Peter. /proc/$pid/ns
Will work on this and respin...

Thanks
Hari