[tip:perfcounters/core] perf_counter: comment the perf_event_type stuff

[Peter Zijlstra]

Commit-ID:  0c593b3411341e3a05a61f5527df36ab02bd11e8
Gitweb:     http://git.kernel.org/tip/0c593b3411341e3a05a61f5527df36ab02bd11e8
Author:     Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Mon, 6 Apr 2009 11:45:08 +0200
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Tue, 7 Apr 2009 10:48:59 +0200

perf_counter: comment the perf_event_type stuff

Describe the event format.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx>
LKML-Reference: <20090406094518.211174347@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>


---
 include/linux/perf_counter.h |   32 ++++++++++++++++++++++++++++++++
 1 files changed, 32 insertions(+), 0 deletions(-)

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index ef4dcbf..8122018 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -208,6 +208,20 @@ struct perf_event_header {
 
 enum perf_event_type {
 
+	/*
+	 * The MMAP events record the PROT_EXEC mappings so that we can
+	 * correlate userspace IPs to code. They have the following structure:
+	 *
+	 * struct {
+	 * 	struct perf_event_header	header;
+	 *
+	 * 	u32				pid, tid;
+	 * 	u64				addr;
+	 * 	u64				len;
+	 * 	u64				pgoff;
+	 * 	char				filename[];
+	 * };
+	 */
 	PERF_EVENT_MMAP			= 1,
 	PERF_EVENT_MUNMAP		= 2,
 
@@ -217,6 +231,24 @@ enum perf_event_type {
 	 *
 	 * These events will have types of the form:
 	 *   PERF_EVENT_COUNTER_OVERFLOW { | __PERF_EVENT_* } *
+	 *
+	 * struct {
+	 * 	struct perf_event_header	header;
+	 *
+	 * 	{ u64			ip;	  } && __PERF_EVENT_IP
+	 * 	{ u32			pid, tid; } && __PERF_EVENT_TID
+	 *
+	 * 	{ u64			nr;
+	 * 	  { u64 event, val; } 	cnt[nr];  } && __PERF_EVENT_GROUP
+	 *
+	 * 	{ u16			nr,
+	 * 				hv,
+	 * 				kernel,
+	 * 				user;
+	 * 	  u64			ips[nr];  } && __PERF_EVENT_CALLCHAIN
+	 *
+	 * 	{ u64			time;     } && __PERF_EVENT_TIME
+	 * };
 	 */
 	PERF_EVENT_COUNTER_OVERFLOW	= 1UL << 31,
 	__PERF_EVENT_IP			= PERF_RECORD_IP,
--
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