perf tools: Add some comments to the event definitions

Just to make it clear that these are _not_ generic event
structures but do rely on the counter configuration.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Corey J Ashford <cjashfor@us.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: stephane eranian <eranian@googlemail.com>
LKML-Reference: <20090813103655.334194326@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/util/event.h

@@ -4,6 +4,9 @@
 #include "util.h"
 #include <linux/list.h>
 
+/*
+ * PERF_SAMPLE_IP | PERF_SAMPLE_TID | *
+ */
 struct ip_event {
 	struct perf_event_header header;
 	u64 ip;
@@ -38,6 +41,9 @@ struct lost_event {
 	u64 lost;
 };
 
+/*
+ * PERF_FORMAT_ENABLED | PERF_FORMAT_RUNNING | PERF_FORMAT_ID
+ */
 struct read_event {
 	struct perf_event_header header;
 	u32 pid,tid;