selftests/resctrl: Add Cache Allocation Technology (CAT) selftest

Cache Allocation Technology (CAT) selftest allocates a portion of
last level cache and starts a benchmark to read each cache
line in this portion of cache. Measure the cache misses in perf and
the misses should be equal to the number of cache lines in this
portion of cache.

We don't use CQM to calculate cache usage because some CAT enabled
platforms don't have CQM.

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>

tools/testing/selftests/resctrl/cache.c

@@ -10,8 +10,105 @@ struct read_format {
 	} values[2];
 };
 
+static struct perf_event_attr pea_llc_miss;
+static struct read_format rf_cqm;
+static int fd_lm;
 char llc_occup_path[1024];
 
+static void initialize_perf_event_attr(void)
+{
+	pea_llc_miss.type = PERF_TYPE_HARDWARE;
+	pea_llc_miss.size = sizeof(struct perf_event_attr);
+	pea_llc_miss.read_format = PERF_FORMAT_GROUP;
+	pea_llc_miss.exclude_kernel = 1;
+	pea_llc_miss.exclude_hv = 1;
+	pea_llc_miss.exclude_idle = 1;
+	pea_llc_miss.exclude_callchain_kernel = 1;
+	pea_llc_miss.inherit = 1;
+	pea_llc_miss.exclude_guest = 1;
+	pea_llc_miss.disabled = 1;
+}
+
+static void ioctl_perf_event_ioc_reset_enable(void)
+{
+	ioctl(fd_lm, PERF_EVENT_IOC_RESET, 0);
+	ioctl(fd_lm, PERF_EVENT_IOC_ENABLE, 0);
+}
+
+static int perf_event_open_llc_miss(pid_t pid, int cpu_no)
+{
+	fd_lm = perf_event_open(&pea_llc_miss, pid, cpu_no, -1,
+				PERF_FLAG_FD_CLOEXEC);
+	if (fd_lm == -1) {
+		perror("Error opening leader");
+		ctrlc_handler(0, NULL, NULL);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int initialize_llc_perf(void)
+{
+	memset(&pea_llc_miss, 0, sizeof(struct perf_event_attr));
+	memset(&rf_cqm, 0, sizeof(struct read_format));
+
+	/* Initialize perf_event_attr structures for HW_CACHE_MISSES */
+	initialize_perf_event_attr();
+
+	pea_llc_miss.config = PERF_COUNT_HW_CACHE_MISSES;
+
+	rf_cqm.nr = 1;
+
+	return 0;
+}
+
+static int reset_enable_llc_perf(pid_t pid, int cpu_no)
+{
+	int ret = 0;
+
+	ret = perf_event_open_llc_miss(pid, cpu_no);
+	if (ret < 0)
+		return ret;
+
+	/* Start counters to log values */
+	ioctl_perf_event_ioc_reset_enable();
+
+	return 0;
+}
+
+/*
+ * get_llc_perf:	llc cache miss through perf events
+ * @cpu_no:		CPU number that the benchmark PID is binded to
+ *
+ * Perf events like HW_CACHE_MISSES could be used to validate number of
+ * cache lines allocated.
+ *
+ * Return: =0 on success.  <0 on failure.
+ */
+static int get_llc_perf(unsigned long *llc_perf_miss)
+{
+	__u64 total_misses;
+
+	/* Stop counters after one span to get miss rate */
+
+	ioctl(fd_lm, PERF_EVENT_IOC_DISABLE, 0);
+
+	if (read(fd_lm, &rf_cqm, sizeof(struct read_format)) == -1) {
+		perror("Could not get llc misses through perf");
+
+		return -1;
+	}
+
+	total_misses = rf_cqm.values[0].value;
+
+	close(fd_lm);
+
+	*llc_perf_miss = total_misses;
+
+	return 0;
+}
+
 /*
  * Get LLC Occupancy as reported by RESCTRL FS
  * For CQM,
@@ -79,9 +176,19 @@ static int print_results_cache(char *filename, int bm_pid,
 
 int measure_cache_vals(struct resctrl_val_param *param, int bm_pid)
 {
-	unsigned long llc_occu_resc = 0, llc_value = 0;
+	unsigned long llc_perf_miss = 0, llc_occu_resc = 0, llc_value = 0;
 	int ret;
 
+	/*
+	 * Measure cache miss from perf.
+	 */
+	if (!strcmp(param->resctrl_val, "cat")) {
+		ret = get_llc_perf(&llc_perf_miss);
+		if (ret < 0)
+			return ret;
+		llc_value = llc_perf_miss;
+	}
+
 	/*
 	 * Measure llc occupancy from resctrl.
 	 */
@@ -97,3 +204,69 @@ int measure_cache_vals(struct resctrl_val_param *param, int bm_pid)
 
 	return 0;
 }
+
+/*
+ * cache_val:		execute benchmark and measure LLC occupancy resctrl
+ * and perf cache miss for the benchmark
+ * @param:		parameters passed to cache_val()
+ *
+ * Return:		0 on success. non-zero on failure.
+ */
+int cat_val(struct resctrl_val_param *param)
+{
+	int malloc_and_init_memory = 1, memflush = 1, operation = 0, ret = 0;
+	char *resctrl_val = param->resctrl_val;
+	pid_t bm_pid;
+
+	if (strcmp(param->filename, "") == 0)
+		sprintf(param->filename, "stdio");
+
+	bm_pid = getpid();
+
+	/* Taskset benchmark to specified cpu */
+	ret = taskset_benchmark(bm_pid, param->cpu_no);
+	if (ret)
+		return ret;
+
+	/* Write benchmark to specified con_mon grp, mon_grp in resctrl FS*/
+	ret = write_bm_pid_to_resctrl(bm_pid, param->ctrlgrp, param->mongrp,
+				      resctrl_val);
+	if (ret)
+		return ret;
+
+	if ((strcmp(resctrl_val, "cat") == 0)) {
+		ret = initialize_llc_perf();
+		if (ret)
+			return ret;
+	}
+
+	/* Test runs until the callback setup() tells the test to stop. */
+	while (1) {
+		if (strcmp(resctrl_val, "cat") == 0) {
+			ret = param->setup(1, param);
+			if (ret) {
+				ret = 0;
+				break;
+			}
+			ret = reset_enable_llc_perf(bm_pid, param->cpu_no);
+			if (ret)
+				break;
+
+			if (run_fill_buf(param->span, malloc_and_init_memory,
+					 memflush, operation, resctrl_val)) {
+				fprintf(stderr, "Error-running fill buffer\n");
+				ret = -1;
+				break;
+			}
+
+			sleep(1);
+			ret = measure_cache_vals(param, bm_pid);
+			if (ret)
+				break;
+		} else {
+			break;
+		}
+	}
+
+	return ret;
+}