From: Peter Zijlstra <peterz@infradead.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nikolay Borisov <kernel@kyup.com>,
Aravinda Prasad <aravinda@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org, rostedt@goodmis.org,
mingo@redhat.com, paulus@samba.org, acme@kernel.org,
hbathini@linux.vnet.ibm.com, ananth@in.ibm.com
Subject: Re: [RFC PATCH 2/2] perf: Filter events based on perf-namespace
Date: Tue, 12 Jul 2016 16:27:53 +0200 [thread overview]
Message-ID: <20160712142753.GT30909@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <8737nf55bu.fsf@x220.int.ebiederm.org>
On Tue, Jul 12, 2016 at 08:55:17AM -0500, Eric W. Biederman wrote:
> I completely misread the description of this, or I would have something
> earlier. For some reason I thought he was talking about the perf
> controller.
>
> As I recall the tricky part of this was to have tracing that was safe
> and usable inside of a container. If you can align a per cgroup with
> your container that is probably sufficient for the select of processes.
>
> At the same time there is a real desire to have identifiers like pids
> translated into the appropriate form for inside of the container.
> Without that translation they are meaningless inside a container.
> Further it is necessary to be certain the trancing that is used is is
> safe for unprivileged users.
>
> I don't think I ever suggested or approved of the concept of a perf
> namespace and that sounds a bit dubious to me.
So perf uses the pid-namespace of the event-creator to report PID/TID
numbers in.
So sys_perf_event_open() -> perf_event_alloc() does
get_pid_ns(task_active_pid_ns(current)) to set event->ns and then we do:
task_{tgid,pid}_nr_ns(p, event->ns) to report the PID/TID resp., see
perf_event_{pid,tid}().
next prev parent reply other threads:[~2016-07-12 14:28 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-14 16:49 [RFC PATCH 0/2] perf: Container-aware tracing support Aravinda Prasad
2016-06-14 16:49 ` [RFC PATCH 1/2] perf/namespaces: Add a new namespace for isolated tracing Aravinda Prasad
2016-06-14 16:49 ` [RFC PATCH 2/2] perf: Filter events based on perf-namespace Aravinda Prasad
2016-06-27 15:50 ` Peter Zijlstra
2016-06-28 11:39 ` Aravinda Prasad
2016-07-12 9:26 ` Aravinda Prasad
2016-07-12 11:47 ` Peter Zijlstra
2016-07-12 12:41 ` Nikolay Borisov
2016-07-12 13:04 ` Peter Zijlstra
2016-07-12 13:55 ` Eric W. Biederman
2016-07-12 14:27 ` Peter Zijlstra [this message]
2016-07-12 16:04 ` Aravinda Prasad
2016-07-12 16:19 ` Aravinda Prasad
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