[RFC/PATCH 01/38] perf tools: Use a software dummy event to track task/mmap events

[Namhyung Kim <namhyung@kernel.org>]

Add APIs for software dummy event to track task/comm/mmap events
separately.  The perf record will use them to save such events in a
separate mmap buffer to make it easy to index.  This is a preparation of
multi-thread support which will come later.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/util/evlist.c | 30 ++++++++++++++++++++++++++++++
 tools/perf/util/evlist.h |  1 +
 tools/perf/util/evsel.h  | 15 +++++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index e7e195d867ea..c5180a29db1b 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -248,6 +248,36 @@ error:
 	return -ENOMEM;
 }
 
+int perf_evlist__add_dummy_tracking(struct perf_evlist *evlist)
+{
+	struct perf_event_attr attr = {
+		.type = PERF_TYPE_SOFTWARE,
+		.config = PERF_COUNT_SW_DUMMY,
+		.exclude_kernel = 1,
+	};
+	struct perf_evsel *evsel;
+
+	event_attr_init(&attr);
+
+	evsel = perf_evsel__new(&attr);
+	if (evsel == NULL)
+		goto error;
+
+	/* use strdup() because free(evsel) assumes name is allocated */
+	evsel->name = strdup("dummy");
+	if (!evsel->name)
+		goto error_free;
+
+	perf_evlist__add(evlist, evsel);
+	perf_evlist__set_tracking_event(evlist, evsel);
+
+	return 0;
+error_free:
+	perf_evsel__delete(evsel);
+error:
+	return -ENOMEM;
+}
+
 static int perf_evlist__add_attrs(struct perf_evlist *evlist,
 				  struct perf_event_attr *attrs, size_t nr_attrs)
 {
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 66bc9d4c0869..414e383885f5 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -75,6 +75,7 @@ void perf_evlist__delete(struct perf_evlist *evlist);
 void perf_evlist__add(struct perf_evlist *evlist, struct perf_evsel *entry);
 void perf_evlist__remove(struct perf_evlist *evlist, struct perf_evsel *evsel);
 int perf_evlist__add_default(struct perf_evlist *evlist);
+int perf_evlist__add_dummy_tracking(struct perf_evlist *evlist);
 int __perf_evlist__add_default_attrs(struct perf_evlist *evlist,
 				     struct perf_event_attr *attrs, size_t nr_attrs);
 
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 7906666580da..8d2445347b0f 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -359,6 +359,21 @@ static inline bool perf_evsel__is_function_event(struct perf_evsel *evsel)
 #undef FUNCTION_EVENT
 }
 
+/**
+ * perf_evsel__is_dummy_tracking - Return whether given evsel is a dummy
+ * event for tracking meta events only
+ *
+ * @evsel - evsel selector to be tested
+ *
+ * Return %true if event is a dummy tracking event
+ */
+static inline bool perf_evsel__is_dummy_tracking(struct perf_evsel *evsel)
+{
+	return evsel->attr.type == PERF_TYPE_SOFTWARE &&
+		evsel->attr.config == PERF_COUNT_SW_DUMMY &&
+		evsel->attr.task == 1 && evsel->attr.mmap == 1;
+}
+
 struct perf_attr_details {
 	bool freq;
 	bool verbose;
-- 
2.6.0