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

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 1/2] perf: add container identifier entry in perf sample data
Date	2016-09-02 16:00 +0200
Message-ID	<scXaF-9t-11@gated-at.bofh.it> (permalink)
References	<sbU5b-7gZ-3@gated-at.bofh.it> <scwk9-7Sa-13@gated-at.bofh.it> <scXaF-9t-7@gated-at.bofh.it>
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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.

> 
> >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?

Thread

[PATCH v2 1/2] perf: add container identifier entry in perf sample  data Hari Bathini <hbathini@linux.vnet.ibm.com> - 2016-08-30 18:30 +0200
  Re: [PATCH v2 1/2] perf: add container identifier entry in perf  sample data Peter Zijlstra <peterz@infradead.org> - 2016-09-01 11:20 +0200
    Re: [PATCH v2 1/2] perf: add container identifier entry in perf  sample data Hari Bathini <hbathini@linux.vnet.ibm.com> - 2016-09-02 16:00 +0200
      Re: [PATCH v2 1/2] perf: add container identifier entry in perf  sample data Peter Zijlstra <peterz@infradead.org> - 2016-09-02 16:00 +0200
        Re: [PATCH v2 1/2] perf: add container identifier entry in perf  sample data Hari Bathini <hbathini@linux.vnet.ibm.com> - 2016-09-02 19:00 +0200

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