From: Peter Zijlstra <peterz@infradead.org>
To: Robert Bragg <robert@sixbynine.org>
Cc: linux-kernel@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
Chris Wilson <chris@chris-wilson.co.uk>,
Rob Clark <robdclark@gmail.com>,
Samuel Pitoiset <samuel.pitoiset@gmail.com>,
Ben Skeggs <bskeggs@redhat.com>
Subject: Re: [RFC PATCH 0/3] Expose gpu counters via perf pmu driver
Date: Thu, 30 Oct 2014 20:08:41 +0100 [thread overview]
Message-ID: <20141030190841.GI23531@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <1413991731-20628-1-git-send-email-robert@sixbynine.org>
On Wed, Oct 22, 2014 at 04:28:48PM +0100, Robert Bragg wrote:
> Our desired permission model seems consistent with perf's current model
> whereby you would need privileges if you want to profile across all gpu
> contexts but not need special permissions to profile your own context.
>
> The awkward part is that it doesn't make sense for us to have userspace
> open a perf event with a specific pid as the way to avoid needing root
> permissions because a side effect of doing this is that the events will
> be dynamically added/deleted so as to only monitor while that process is
> scheduled and that's not really meaningful when we're monitoring the
> gpu.
There is precedent in PERF_FLAG_PID_CGROUP to replace the pid argument
with a fd to your object.
And do I take it right that if you're able/allowed/etc.. to open/have
the fd to the GPU/DRM/DRI whatever context you have the right
credentials to also observe these counters?
> Conceptually I suppose we want to be able to open an event that's not
> associated with any cpu or process, but to keep things simple and fit
> with perf's current design, the pmu I have a.t.m expects an event to be
> opened for a specific cpu and unspecified process.
There are no actual scheduling ramifications right? Let me ponder his
for a little while more..
next prev parent reply other threads:[~2014-10-30 19:08 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-22 15:28 [RFC PATCH 0/3] Expose gpu counters via perf pmu driver Robert Bragg
2014-10-22 15:28 ` [RFC PATCH 1/3] perf: export perf_event_overflow Robert Bragg
2014-10-22 15:28 ` [RFC PATCH 2/3] perf: Add PERF_PMU_CAP_IS_DEVICE flag Robert Bragg
2014-10-22 15:28 ` [RFC PATCH 3/3] i915: Expose PMU for Observation Architecture Robert Bragg
2014-10-23 7:47 ` Chris Wilson
2014-10-24 2:33 ` Robert Bragg
2014-10-24 6:56 ` Chris Wilson
2014-10-23 5:58 ` [RFC PATCH 0/3] Expose gpu counters via perf pmu driver Ingo Molnar
2014-10-24 13:39 ` Robert Bragg
2014-10-30 19:08 ` Peter Zijlstra [this message]
2014-11-03 21:47 ` Robert Bragg
2014-11-05 12:33 ` Peter Zijlstra
2014-11-06 0:37 ` Robert Bragg
2014-11-10 11:13 ` Ingo Molnar
2014-11-12 23:33 ` Robert Bragg
2014-11-16 9:27 ` Ingo Molnar
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