Messages in this thread |  | | Date | Thu, 30 Oct 2014 20:08:41 +0100 | From | Peter Zijlstra <> | Subject | Re: [RFC PATCH 0/3] Expose gpu counters via perf pmu driver |
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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..
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