Re: [RFC][PATCH] perf: sysfs type id

[Peter Zijlstra]

On Wed, 2010-11-10 at 15:10 +0100, Peter Zijlstra wrote:
> On Wed, 2010-11-10 at 14:01 +0100, Stephane Eranian wrote:
> > Peter,
> 
> > > 6
> > 
> > And then, what do you do with 6?
> > I assume you have to pass it in the attr struct.
> 
> perf_event_attr::type, as said in the initial changelog.
> 
> > How do you plan on doing this while keeping what is already there?
> 
> +       if (type < 0) {
> +               err = idr_get_new_above(&pmu_idr, pmu, PERF_TYPE_MAX, &type);
> 
> and
> 
> +       rcu_read_lock();
> +       pmu = idr_find(&pmu_idr, event->attr.type);
> +       rcu_read_unlock();
> +       if (pmu)
> +               goto unlock;
> 
> 
> So we start dynamic IDs at the top of the static range, and only do
> dynamic IDs for those that don't already have a static number.

Also note that I picked:

+       perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW);

as the CPU type, since we can easily provide the raw values in any
listed events, eg.

# cat /sys/.../cpu/events/cycles
0x003c


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