Messages in this thread | | | Date | Mon, 21 Nov 2011 20:31:45 +0000 | From | Will Deacon <> | Subject | Re: [RFC][PATCH 2/6] perf, arch: Rework perf_event_index() |
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On Mon, Nov 21, 2011 at 07:18:10PM +0000, Peter Zijlstra wrote: > But does ARM have a read PMU counter from userspace > instruction/capability?
In ARMv7, you can enable user access to the performance counters but the access is R/W so I don't think it's something we want to do (could interfere with another task doing system-wide profiling).
> Lacking that its all moot of course. If it does, it would be nice to > have an ARM version of patch 6.
Well we'd need a way to get around the all-or-nothing user access to the PMU and also the fact that we don't always have a user-readable clocksource.
Either way, the event counters are indexed from 0 on ARMv7 so we should use perf_event_idx_default.
Will
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