[PATCH 3/5] selftests/damon/access_memory: add repeat mode

[SeongJae Park <sj@kernel.org>]

'access_memory' is an artificial memory access generator program that is
used for a few DAMON selftests.  It accesses a given number of regions
one by one only once, and exits.  Depending on systems, the test
workload may exit faster than expected, making the tests unreliable.
For reliable control of the artificial memory access pattern, add a mode
to make it repeat running.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 tools/testing/selftests/damon/access_memory.c | 29 ++++++++++++++-----
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/damon/access_memory.c b/tools/testing/selftests/damon/access_memory.c
index 56b17e8fe1be..567793b11107 100644
--- a/tools/testing/selftests/damon/access_memory.c
+++ b/tools/testing/selftests/damon/access_memory.c
@@ -8,6 +8,11 @@
 #include <string.h>
 #include <time.h>
 
+enum access_mode {
+	ACCESS_MODE_ONCE,
+	ACCESS_MODE_REPEAT,
+};
+
 int main(int argc, char *argv[])
 {
 	char **regions;
@@ -15,10 +20,12 @@ int main(int argc, char *argv[])
 	int nr_regions;
 	int sz_region;
 	int access_time_ms;
+	enum access_mode mode = ACCESS_MODE_ONCE;
+
 	int i;
 
-	if (argc != 4) {
-		printf("Usage: %s <number> <size (bytes)> <time (ms)>\n",
+	if (argc < 4) {
+		printf("Usage: %s <number> <size (bytes)> <time (ms)> [mode]\n",
 				argv[0]);
 		return -1;
 	}
@@ -27,15 +34,21 @@ int main(int argc, char *argv[])
 	sz_region = atoi(argv[2]);
 	access_time_ms = atoi(argv[3]);
 
+	if (argc > 4 && !strcmp(argv[4], "repeat"))
+		mode = ACCESS_MODE_REPEAT;
+
 	regions = malloc(sizeof(*regions) * nr_regions);
 	for (i = 0; i < nr_regions; i++)
 		regions[i] = malloc(sz_region);
 
-	for (i = 0; i < nr_regions; i++) {
-		start_clock = clock();
-		while ((clock() - start_clock) * 1000 / CLOCKS_PER_SEC <
-				access_time_ms)
-			memset(regions[i], i, sz_region);
-	}
+	do {
+		for (i = 0; i < nr_regions; i++) {
+			start_clock = clock();
+			while ((clock() - start_clock) * 1000 / CLOCKS_PER_SEC
+					< access_time_ms)
+				memset(regions[i], i, sz_region);
+		}
+	} while (mode == ACCESS_MODE_REPEAT);
+
 	return 0;
 }
-- 
2.47.3