[PATCH 14/22] selftests/resctrl: Create cache_alloc_size() helper

[Ilpo Järvinen]

CAT and CMT tests calculate the span size from the n-bits cache
allocation on their own.

Add cache_alloc_size() helper which calculates size of the cache
allocation for the given number of bits to avoid duplicating code.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---
 tools/testing/selftests/resctrl/cache.c    | 27 ++++++++++++++++++++++
 tools/testing/selftests/resctrl/cat_test.c |  8 +++++--
 tools/testing/selftests/resctrl/cmt_test.c |  4 +++-
 tools/testing/selftests/resctrl/resctrl.h  |  2 ++
 4 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cache.c b/tools/testing/selftests/resctrl/cache.c
index 6bc912de38be..5e59c239961c 100644
--- a/tools/testing/selftests/resctrl/cache.c
+++ b/tools/testing/selftests/resctrl/cache.c
@@ -15,6 +15,33 @@ static struct read_format rf_cqm;
 static int fd_lm;
 char llc_occup_path[1024];
 
+/*
+ * cache_alloc_size - Calculate slice size for given cache slice mask
+ * @cpu_no:		CPU number
+ * @cache_type:		Cache level L2/L3
+ * @slice_mask:		Cache slice mask
+ * @slice_size:		Slice size returned on success
+ *
+ * Returns: 0 on success with @slize_size filled, non-zero on error.
+ */
+int cache_alloc_size(int cpu_no, char *cache_type, unsigned long slice_mask,
+		     unsigned long *slice_size)
+{
+	unsigned long cache_size, full_mask;
+	int ret;
+
+	ret = get_cbm_mask(cache_type, &full_mask);
+	if (ret)
+		return ret;
+
+	ret = get_cache_size(cpu_no, cache_type, &cache_size);
+	if (ret)
+		return ret;
+
+	*slice_size = cache_size * count_bits(slice_mask) / count_bits(full_mask);
+	return 0;
+}
+
 static void initialize_perf_event_attr(void)
 {
 	pea_llc_miss.type = PERF_TYPE_HARDWARE;
diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
index 7fa693e4de8f..1c736f3f3c05 100644
--- a/tools/testing/selftests/resctrl/cat_test.c
+++ b/tools/testing/selftests/resctrl/cat_test.c
@@ -146,7 +146,9 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
 	/* Set param values for parent thread which will be allocated bitmask
 	 * with (max_bits - n) bits
 	 */
-	param.span = cache_size * (count_of_bits - n) / count_of_bits;
+	ret = cache_alloc_size(cpu_no, cache_type, l_mask, &param.span);
+	if (ret)
+		return ret;
 	strcpy(param.ctrlgrp, "c2");
 	strcpy(param.mongrp, "m2");
 	strcpy(param.filename, RESULT_FILE_NAME2);
@@ -167,7 +169,9 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
 		param.mask = l_mask_1;
 		strcpy(param.ctrlgrp, "c1");
 		strcpy(param.mongrp, "m1");
-		param.span = cache_size * n / count_of_bits;
+		ret = cache_alloc_size(cpu_no, cache_type, l_mask_1, &param.span);
+		if (ret)
+			return ret;
 		strcpy(param.filename, RESULT_FILE_NAME1);
 		param.num_of_runs = 0;
 		param.cpu_no = sibling_cpu_no;
diff --git a/tools/testing/selftests/resctrl/cmt_test.c b/tools/testing/selftests/resctrl/cmt_test.c
index 5026d9863c6f..b5071594aa76 100644
--- a/tools/testing/selftests/resctrl/cmt_test.c
+++ b/tools/testing/selftests/resctrl/cmt_test.c
@@ -110,10 +110,12 @@ int cmt_resctrl_val(int cpu_no, int n, char **benchmark_cmd)
 		.mum_resctrlfs	= false,
 		.filename	= RESULT_FILE_NAME,
 		.mask		= ~(long_mask << n) & long_mask,
-		.span		= cache_size * n / count_of_bits,
 		.num_of_runs	= 0,
 		.setup		= cmt_setup,
 	};
+	ret = cache_alloc_size(cpu_no, "L3", param.mask, &param.span);
+	if (ret)
+		return ret;
 
 	if (strcmp(benchmark_cmd[0], "fill_buf") == 0)
 		sprintf(benchmark_cmd[1], "%lu", param.span);
diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
index 6c23ceff2a04..605b09d4538a 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -110,6 +110,8 @@ int mba_schemata_change(int cpu_no, char *bw_report, char **benchmark_cmd);
 void mba_test_cleanup(void);
 int get_cbm_mask(char *cache_type, unsigned long *mask);
 int get_cache_size(int cpu_no, char *cache_type, unsigned long *cache_size);
+int cache_alloc_size(int cpu_no, char *cache_type, unsigned long slice_mask,
+		     unsigned long *slice_size);
 void ctrlc_handler(int signum, siginfo_t *info, void *ptr);
 int cat_val(struct resctrl_val_param *param);
 void cat_test_cleanup(void);
-- 
2.30.2