[PATCH v18 08/14] 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>
---
 include/trace/events/damon.h | 43 ++++++++++++++++++++++++++++++++++++
 mm/damon.c                   |  4 ++++
 2 files changed, 47 insertions(+)
 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..40b249a28b30
--- /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_task *t, struct damon_region *r,
+		unsigned int nr_regions),
+
+	TP_ARGS(t, r, nr_regions),
+
+	TP_STRUCT__entry(
+		__field(int, pid)
+		__field(unsigned int, nr_regions)
+		__field(unsigned long, start)
+		__field(unsigned long, end)
+		__field(unsigned int, nr_accesses)
+	),
+
+	TP_fast_assign(
+		__entry->pid = t->pid;
+		__entry->nr_regions = nr_regions;
+		__entry->start = r->ar.start;
+		__entry->end = r->ar.end;
+		__entry->nr_accesses = r->nr_accesses;
+	),
+
+	TP_printk("pid=%d nr_regions=%u %lu-%lu: %u", __entry->pid,
+			__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.c b/mm/damon.c
index 55ecfab64220..00df1a4c3d5c 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -19,6 +19,8 @@
 
 #define pr_fmt(fmt) "damon: " fmt
 
+#define CREATE_TRACE_POINTS
+
 #include <linux/damon.h>
 #include <linux/delay.h>
 #include <linux/kthread.h>
@@ -29,6 +31,7 @@
 #include <linux/sched/mm.h>
 #include <linux/sched/task.h>
 #include <linux/slab.h>
+#include <trace/events/damon.h>
 
 /* Minimal region size.  Every damon_region is aligned by this. */
 #define MIN_REGION PAGE_SIZE
@@ -791,6 +794,7 @@ static void kdamond_reset_aggregated(struct damon_ctx *c)
 			damon_write_rbuf(c, &r->ar.end, sizeof(r->ar.end));
 			damon_write_rbuf(c, &r->nr_accesses,
 					sizeof(r->nr_accesses));
+			trace_damon_aggregated(t, r, nr);
 			r->nr_accesses = 0;
 		}
 	}
-- 
2.17.1