[PATCH V2 13/19] selftests/resctrl: Dynamically select buffer size for CAT test

[Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>]

Presently, while running CAT test case, if user hasn't given any input for
'-n' option, the test defaults to 5 bits to determine the buffer size that
is used during test. This might become a problem on system with max_cbm
mask <= 5 bits. Hence, instead of statically running always with 5 bits,
change it such that the buffer size is always half of the cache size.

Please note that CMT test is still hard coded with 5 bits. It will change
in subsequent patches that change CMT test.

Fixes: 790bf585b0ee ("selftests/resctrl: Add Cache Allocation Technology (CAT) selftest")
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
---
 tools/testing/selftests/resctrl/cat_test.c      | 5 ++++-
 tools/testing/selftests/resctrl/resctrl_tests.c | 8 ++++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
index 5da43767b973..1bce84e23783 100644
--- a/tools/testing/selftests/resctrl/cat_test.c
+++ b/tools/testing/selftests/resctrl/cat_test.c
@@ -151,7 +151,10 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
 	/* Get max number of bits from default-cabm mask */
 	count_of_bits = count_bits(long_mask);
 
-	if (n < 1 || n > count_of_bits - 1) {
+	if (!n)
+		n = count_of_bits / 2;
+
+	if (n > count_of_bits - 1) {
 		printf("Invalid input value for no_of_bits n!\n");
 		printf("Please Enter value in range 1 to %d\n",
 		       count_of_bits - 1);
diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c
index f005ba2b41ec..fb7703413be7 100644
--- a/tools/testing/selftests/resctrl/resctrl_tests.c
+++ b/tools/testing/selftests/resctrl/resctrl_tests.c
@@ -57,7 +57,7 @@ void tests_cleanup(void)
 int main(int argc, char **argv)
 {
 	bool has_ben = false, mbm_test = true, mba_test = true, cmt_test = true;
-	int res, c, cpu_no = 1, span = 250, argc_new = argc, i, no_of_bits = 5;
+	int res, c, cpu_no = 1, span = 250, argc_new = argc, i, no_of_bits = 0;
 	char *benchmark_cmd[BENCHMARK_ARGS], bw_report[64], bm_type[64];
 	char benchmark_cmd_area[BENCHMARK_ARGS][BENCHMARK_ARG_SIZE];
 	int ben_ind, ben_count;
@@ -106,6 +106,10 @@ int main(int argc, char **argv)
 			break;
 		case 'n':
 			no_of_bits = atoi(optarg);
+			if (no_of_bits <= 0) {
+				printf("Bail out! invalid argument for no_of_bits\n");
+				return -1;
+			}
 			break;
 		case 'h':
 			cmd_help();
@@ -188,7 +192,7 @@ int main(int argc, char **argv)
 		printf("# Starting CMT test ...\n");
 		if (!has_ben)
 			sprintf(benchmark_cmd[5], "%s", "cmt");
-		res = cmt_resctrl_val(cpu_no, no_of_bits, benchmark_cmd);
+		res = cmt_resctrl_val(cpu_no, 5, benchmark_cmd);
 		printf("%sok CMT: test\n", res ? "not " : "");
 		cmt_test_cleanup();
 		tests_run++;
-- 
2.19.1