[PATCH V2 1/3] perf: add a dummy software event to keep tracking

[Adrian Hunter <adrian.hunter@intel.com>]

When an event is disabled the "tracking" events
selected by the 'mmap', 'comm' and 'task' bits of
struct perf_event_attr, are also disabled.  However,
the information those events provide is necessary to
resolve symbols for when the main event is re-enabled.

The "tracking" events can be kept enabled by putting
them on another event, but that requires an event
that otherwise does nothing.  A new software event
PERF_COUNT_SW_DUMMY is added for that purpose.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
---
 include/uapi/linux/perf_event.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 42cb7b6..108c4bc 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -109,6 +109,7 @@ enum perf_sw_ids {
 	PERF_COUNT_SW_PAGE_FAULTS_MAJ		= 6,
 	PERF_COUNT_SW_ALIGNMENT_FAULTS		= 7,
 	PERF_COUNT_SW_EMULATION_FAULTS		= 8,
+	PERF_COUNT_SW_DUMMY			= 9,
 
 	PERF_COUNT_SW_MAX,			/* non-ABI */
 };
-- 
1.7.11.7