[PATCH v24 06/14] mm/damon: Add a tracepoint

[SeongJae Park <sjpark@amazon.com>]

From: SeongJae Park <sjpark@amazon.de>

This commit adds a tracepoint for DAMON.  It traces the monitoring
results of each region for each aggregation interval.  Using this, DAMON
can easily integrated with tracepoints supporting tools such as perf.

Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Leonard Foerster <foersleo@amazon.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 include/trace/events/damon.h | 43 ++++++++++++++++++++++++++++++++++++
 mm/damon/core.c              |  7 +++++-
 2 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 include/trace/events/damon.h

diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h
new file mode 100644
index 000000000000..2f422f4f1fb9
--- /dev/null
+++ b/include/trace/events/damon.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM damon
+
+#if !defined(_TRACE_DAMON_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_DAMON_H
+
+#include <linux/damon.h>
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(damon_aggregated,
+
+	TP_PROTO(struct damon_target *t, struct damon_region *r,
+		unsigned int nr_regions),
+
+	TP_ARGS(t, r, nr_regions),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, target_id)
+		__field(unsigned int, nr_regions)
+		__field(unsigned long, start)
+		__field(unsigned long, end)
+		__field(unsigned int, nr_accesses)
+	),
+
+	TP_fast_assign(
+		__entry->target_id = t->id;
+		__entry->nr_regions = nr_regions;
+		__entry->start = r->ar.start;
+		__entry->end = r->ar.end;
+		__entry->nr_accesses = r->nr_accesses;
+	),
+
+	TP_printk("target_id=%lu nr_regions=%u %lu-%lu: %u",
+			__entry->target_id, __entry->nr_regions,
+			__entry->start, __entry->end, __entry->nr_accesses)
+);
+
+#endif /* _TRACE_DAMON_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/mm/damon/core.c b/mm/damon/core.c
index b36b6bdd94e2..912112662d0c 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -13,6 +13,9 @@
 #include <linux/random.h>
 #include <linux/slab.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/damon.h>
+
 /* Get a random number in [l, r) */
 #define damon_rand(l, r) (l + prandom_u32_max(r - l))
 
@@ -388,8 +391,10 @@ static void kdamond_reset_aggregated(struct damon_ctx *c)
 	damon_for_each_target(t, c) {
 		struct damon_region *r;
 
-		damon_for_each_region(r, t)
+		damon_for_each_region(r, t) {
+			trace_damon_aggregated(t, r, damon_nr_regions(t));
 			r->nr_accesses = 0;
+		}
 	}
 }
 
-- 
2.17.1