[tip:perf/core] perf events: Add PERF_COUNT_HW_REF_CPU_CYCLES generic PMU event

[tip-bot for Stephane Eranian <eranian@google.com>]

Commit-ID:  c37e17497e01fc0f5d2d6feb5723b210b3ab8890
Gitweb:     http://git.kernel.org/tip/c37e17497e01fc0f5d2d6feb5723b210b3ab8890
Author:     Stephane Eranian <eranian@google.com>
AuthorDate: Sun, 11 Dec 2011 00:28:52 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 21 Dec 2011 10:26:37 +0100

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>
---
 include/linux/perf_event.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 564769c..0885561 100644
--- 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 */
 };