perf_counter: request for three more sample data options

From: Corey Ashford
Date: Thu Apr 02 2009 - 21:46:52 EST


Currently, perf_counter has the ability to record the following on event counter overflow:

Instruction Pointer
Call chain
Group counter values
Thread id

To give perf_counter similar capabilities to perfmon2's default sampling module, I'd like the following additional sample data to be added.

Time stamp
CPU number
Thread Group Id

I'd suggest the following

enum perf_counter_record_format {
PERF_RECORD_IP = 1U << 0,
PERF_RECORD_TID = 1U << 1,
PERF_RECORD_TGID = 1U << 2,
- PERF_RECORD_GROUP = 1U << 2,
+ PERF_RECORD_GROUP = 1U << 3,
- PERF_RECORD_CALLCHAIN = 1U << 3,
+ PERF_RECORD_CALLCHAIN = 1U << 4,
+ PERF_RECORD_CPU_ID = 1U << 5,
+ PERF_RECORD_TIMESTAMP = 1U << 6,
};

And of course the obvious changes to perf_event_type.

I would expect that CPU ID would be 32 bits, and the timestamp to be the 64-bit current time. TGID is the same size as TID.

I am guessing the only difficult thing here would be obtaining the current time from an IRQ, especially NMI handler. Is this difficult?


--
Regards,

- Corey

Corey Ashford
Software Engineer
IBM Linux Technology Center, Linux Toolchain
Beaverton, OR
503-578-3507
cjashfor@xxxxxxxxxx

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