Re: [RFC PATCH 2/2] perf: Filter events based on perf-namespace

From	Nikolay Borisov <kernel@kyup.com>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH 2/2] perf: Filter events based on perf-namespace
Date	2016-07-12 14:50 +0200
Message-ID	<rU5iq-4W1-21@gated-at.bofh.it> (permalink)
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On 07/12/2016 02:47 PM, Peter Zijlstra wrote:
> On Tue, Jul 12, 2016 at 02:56:17PM +0530, Aravinda Prasad wrote:
>>
>>
>> On Monday 27 June 2016 09:20 PM, Peter Zijlstra wrote:
>>> On Tue, Jun 14, 2016 at 10:19:51PM +0530, Aravinda Prasad wrote:
>>>> Whenever perf tool is executed inside a container, this
>>>> patch restricts the events to the perf-namespace in which
>>>> the perf tool is executing.
>>>>
>>>> This patch is based on the existing support available
>>>> for tracing with cgroups.
>>>>
>>>> TODO:
>>>>     - Avoid code duplication.
>>>
>>> Can't you, at perf_event_open() time, convert a per-cpu event into a
>>> per-cpu-per-cgroup event for these namespace thingies?
>>>
>>> That seems to immediately and completely remove all that duplication.
>>
>> Sorry for the delay in the response.
>>
>> I was looking into a way how a per-cpu event can be converted to
>> per-cpu-per-cgroup event at perf_event_open() but could not figure out
>> how to do this conversion. The cgroup event expects the fd of the cgroup
>> directory in cgroupfs and in this case we don't have any fd passed in.
>> Not sure if I am missing anything.
> 
> Would not the current namespace have a link to the correct cgroup?
> Wasn't that the entire point of the namespace thing?

Namespaces and cgroups are completely orthogonal to one another. Also in
the v1 of cgroups it's possible to have a process member of more than 1
cgroup.

>

Thread

Re: [RFC PATCH 2/2] perf: Filter events based on perf-namespace Aravinda Prasad <aravinda@linux.vnet.ibm.com> - 2016-07-12 11:30 +0200
  Re: [RFC PATCH 2/2] perf: Filter events based on perf-namespace Peter Zijlstra <peterz@infradead.org> - 2016-07-12 13:50 +0200
    Re: [RFC PATCH 2/2] perf: Filter events based on perf-namespace Nikolay Borisov <kernel@kyup.com> - 2016-07-12 14:50 +0200
      Re: [RFC PATCH 2/2] perf: Filter events based on perf-namespace Peter Zijlstra <peterz@infradead.org> - 2016-07-12 15:10 +0200
        Re: [RFC PATCH 2/2] perf: Filter events based on perf-namespace ebiederm@xmission.com (Eric W. Biederman) - 2016-07-12 16:10 +0200
          Re: [RFC PATCH 2/2] perf: Filter events based on perf-namespace Peter Zijlstra <peterz@infradead.org> - 2016-07-12 16:30 +0200
            Re: [RFC PATCH 2/2] perf: Filter events based on perf-namespace Aravinda Prasad <aravinda@linux.vnet.ibm.com> - 2016-07-12 18:10 +0200
        Re: [RFC PATCH 2/2] perf: Filter events based on perf-namespace Aravinda Prasad <aravinda@linux.vnet.ibm.com> - 2016-07-12 18:30 +0200

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