Messages in this thread | | | Subject | Re: [RFC][PATCH 3/9] perf: export registerred pmus via sysfs | From | Peter Zijlstra <> | Date | Mon, 10 May 2010 13:27:04 +0200 |
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On Mon, 2010-05-10 at 18:26 +0800, Lin Ming wrote:
> > No, I'm assuming there is only 1 PMU per CPU. Corey is the expert on > > crazy hardware though, but I think the sanest way is to extend the CPU > > topology if there's more structure to it. > > But our goal is to support multiple pmus, don't we need to assume there > are more than 1 PMU per CPU?
No, because as I said, then its ambiguous what pmu you want. If you have that, you need to extend your topology information.
Anyway, I talked with Ingo on this and he'd like to see this somewhat extended.
Instead of a pmu_id field, which we pass into a new perf_event_attr::pmu_id field, how about creating an event_source sysfs class. Then each class can have an event_source_id and a hierarchy of 'generic' events.
We'd start using the PERF_TYPE_ space for this and express the PERF_COUNT_ space in the event attributes found inside that class.
That way we can include all the existing event enumerations into this as well.
This way we can create:
/sys/devices/system/cpu/cpuN/cpu_hardware_events cpu_hardware_events/event_source_id cpu_hardware_events/cpu_cycles cpu_hardware_events/instructions /...
/sys/devices/system/cpu/cpuN/cpu_raw_events cpu_raw_events/event_source_id
These would match the current PERF_TYPE_* values for compatibility
For new PMUs we can start a dynamic range of PERF_TYPE_ (say at 64k but that's not ABI and can be changed at any time, we've got u32 to play with).
For uncore this would result in:
/sys/devices/system/node/nodeN/node_raw_events node_raw_events/event_source_id
and maybe:
/sys/devices/system/node/nodeN/node_events node_events/event_source_id node_events/local_misses /local_hits /remote_misses /remote_hits /...
The software events and tracepoints and kprobes stuff we could hang off of /sys/kernel/ or something
So your registration would indeed look like something:
perf_event_register_pmu(struct pmu *pmu, int type),
where type would normally be -1 (dynamic) but would be PERF_TYPE_ for those already laid down in ABI.
This approach will also give us a good overview in /sys/class/event_source/, which will be a flat listing of all existing event sources.
Does this make sense?
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