[RFC] Extending ARM perf-events for multiple PMUs

[Ashwin Chaugule]

Hi Peter,

On 4/9/2011 7:40 AM, Peter Zijlstra wrote:
> 
> So the perf core supports multiple hardware PMUs, but currently only one
> of which can do per-task sampling, if you've got multiple CPU local PMUs
> we need to do a little extra.

Would this restriction be removed if task_struct->perf_event_ctxp[] had
more entries for each PMU_TYPE ?

On a related note, I haven't had time yet to look deeper for a proper fix
for the stale perf_event_ctx pointer issue, other than the one liner in
perf_task_event_sched_in() we discussed about, but that'll need fixing
before more PMU's start popping up.


> What we do for the events is map the provided CPU number to a memory
> controller (cpu_to_node() does that for our case), and then use the
> first online cpu in that node mask to drive the event.

I suppose you're referring to the uncore patches here.
So only one CPU has access to the uncore PMU at a time ?


Cheers,
Ashwin


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