perf events: Add PERF_COUNT_HW_REF_CPU_CYCLES generic PMU event

This event counts the number of reference core cpu cycles.
Reference means that the event increments at a constant rate which
is not subject to core CPU frequency adjustments. The event may
not count when the processor is in halted (low power) state.
As such, it may not be equivalent to wall clock time. However,
when the processor is not halted state, the event keeps
a constant correlation with wall clock time.

Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1323559734-3488-3-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 564769cdb47387138af3da5c624d3a11ce2a6d02..08855613ceb32ed66e425eb41f69206d6feb61da 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -54,6 +54,7 @@ enum perf_hw_id {
        PERF_COUNT_HW_BUS_CYCLES                = 6,
        PERF_COUNT_HW_STALLED_CYCLES_FRONTEND   = 7,
        PERF_COUNT_HW_STALLED_CYCLES_BACKEND    = 8,
+       PERF_COUNT_HW_REF_CPU_CYCLES            = 9,
 
        PERF_COUNT_HW_MAX,                      /* non-ABI */
 };