selftests/resctrl: Add Cache QoS Monitoring (CQM) selftest

Cache QoS Monitoring (CQM) selftest starts stressful cache benchmark
with specified size of memory to access the cache. Last Level cache
occupancy reported by CQM should be close to the size of the memory.

Co-developed-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Co-developed-by: Babu Moger <babu.moger@amd.com>
Signed-off-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, 99 insertions, 0 deletions

diff --git a/tools/testing/selftests/resctrl/cache.c b/tools/testing/selftests/resctrl/cache.c
new file mode 100644
index 000000000000..d7719219ab51
--- /dev/null
+++ b/tools/testing/selftests/resctrl/cache.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <stdint.h>
+#include "resctrl.h"
+
+struct read_format {
+	__u64 nr;			/* The number of events */
+	struct {
+		__u64 value;		/* The value of the event */
+	} values[2];
+};
+
+char llc_occup_path[1024];
+
+/*
+ * Get LLC Occupancy as reported by RESCTRL FS
+ * For CQM,
+ * 1. If con_mon grp and mon grp given, then read from mon grp in
+ * con_mon grp
+ * 2. If only con_mon grp given, then read from con_mon grp
+ * 3. If both not given, then read from root con_mon grp
+ * For CAT,
+ * 1. If con_mon grp given, then read from it
+ * 2. If con_mon grp not given, then read from root con_mon grp
+ *
+ * Return: =0 on success.  <0 on failure.
+ */
+static int get_llc_occu_resctrl(unsigned long *llc_occupancy)
+{
+	FILE *fp;
+
+	fp = fopen(llc_occup_path, "r");
+	if (!fp) {
+		perror("Failed to open results file");
+
+		return errno;
+	}
+	if (fscanf(fp, "%lu", llc_occupancy) <= 0) {
+		perror("Could not get llc occupancy");
+		fclose(fp);
+
+		return -1;
+	}
+	fclose(fp);
+
+	return 0;
+}
+
+/*
+ * print_results_cache:	the cache results are stored in a file
+ * @filename:		file that stores the results
+ * @bm_pid:		child pid that runs benchmark
+ * @llc_value:		perf miss value /
+ *			llc occupancy value reported by resctrl FS
+ *
+ * Return:		0 on success. non-zero on failure.
+ */
+static int print_results_cache(char *filename, int bm_pid,
+			       unsigned long llc_value)
+{
+	FILE *fp;
+
+	if (strcmp(filename, "stdio") == 0 || strcmp(filename, "stderr") == 0) {
+		printf("Pid: %d \t LLC_value: %lu\n", bm_pid,
+		       llc_value);
+	} else {
+		fp = fopen(filename, "a");
+		if (!fp) {
+			perror("Cannot open results file");
+
+			return errno;
+		}
+		fprintf(fp, "Pid: %d \t llc_value: %lu\n", bm_pid, llc_value);
+		fclose(fp);
+	}
+
+	return 0;
+}
+
+int measure_cache_vals(struct resctrl_val_param *param, int bm_pid)
+{
+	unsigned long llc_occu_resc = 0, llc_value = 0;
+	int ret;
+
+	/*
+	 * Measure llc occupancy from resctrl.
+	 */
+	if (!strcmp(param->resctrl_val, "cqm")) {
+		ret = get_llc_occu_resctrl(&llc_occu_resc);
+		if (ret < 0)
+			return ret;
+		llc_value = llc_occu_resc;
+	}
+	ret = print_results_cache(param->filename, bm_pid, llc_value);
+	if (ret)
+		return ret;
+
+	return 0;
+}