selftests/resctrl: Don't hard code value of "no_of_bits" variable

Cache related tests (like CAT and CMT) depend on a variable called
no_of_bits to run. no_of_bits defines the number of contiguous bits
that should be set in the CBM mask and a user can pass a value for
no_of_bits using -n command line argument. If a user hasn't passed any
value, it defaults to 5 (randomly chosen value).

Hard coding no_of_bits to 5 will make the cache tests fail to run on
systems that support maximum cbm mask that is less than or equal to 5 bits.
Hence, don't hard code no_of_bits value.

If a user passes a value for "no_of_bits" using -n option, use it.
Otherwise, no_of_bits is equal to half of the maximum number of bits in
the cbm mask.

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

Tested-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
index 090d3afc7a78..04d706b4f10e 100644
--- a/tools/testing/selftests/resctrl/cat_test.c
+++ b/tools/testing/selftests/resctrl/cat_test.c
@@ -130,7 +130,10 @@ 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) {
 		ksft_print_msg("Invalid input value for no_of_bits n!\n");
 		ksft_print_msg("Please enter value in range 1 to %d\n",
 			       count_of_bits - 1);