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>

1 files changed, 250 insertions, 0 deletions

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
new file mode 100644
index 000000000000..c194fcc42407
--- /dev/null
+++ b/tools/testing/selftests/resctrl/cat_test.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Cache Allocation Technology (CAT) test
+ *
+ * Copyright (C) 2018 Intel Corporation
+ *
+ * Authors:
+ *    Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>,
+ *    Fenghua Yu <fenghua.yu@intel.com>
+ */
+#include "resctrl.h"
+#include <unistd.h>
+
+#define RESULT_FILE_NAME1	"result_cat1"
+#define RESULT_FILE_NAME2	"result_cat2"
+#define NUM_OF_RUNS		5
+#define MAX_DIFF_PERCENT	4
+#define MAX_DIFF		1000000
+
+int count_of_bits;
+char cbm_mask[256];
+unsigned long long_mask;
+unsigned long cache_size;
+
+/*
+ * Change schemata. Write schemata to specified
+ * con_mon grp, mon_grp in resctrl FS.
+ * Run 5 times in order to get average values.
+ */
+static int cat_setup(int num, ...)
+{
+	struct resctrl_val_param *p;
+	char schemata[64];
+	va_list param;
+	int ret = 0;
+
+	va_start(param, num);
+	p = va_arg(param, struct resctrl_val_param *);
+	va_end(param);
+
+	/* Run NUM_OF_RUNS times */
+	if (p->num_of_runs >= NUM_OF_RUNS)
+		return -1;
+
+	if (p->num_of_runs == 0) {
+		sprintf(schemata, "%lx", p->mask);
+		ret = write_schemata(p->ctrlgrp, schemata, p->cpu_no,
+				     p->resctrl_val);
+	}
+	p->num_of_runs++;
+
+	return ret;
+}
+
+static void show_cache_info(unsigned long sum_llc_perf_miss, int no_of_bits,
+			    unsigned long span)
+{
+	unsigned long allocated_cache_lines = span / 64;
+	unsigned long avg_llc_perf_miss = 0;
+	float diff_percent;
+
+	avg_llc_perf_miss = sum_llc_perf_miss / (NUM_OF_RUNS - 1);
+	diff_percent = ((float)allocated_cache_lines - avg_llc_perf_miss) /
+				allocated_cache_lines * 100;
+
+	printf("%sok CAT: cache miss rate within %d%%\n",
+	       abs((int)diff_percent) > MAX_DIFF_PERCENT ? "not " : "",
+	       MAX_DIFF_PERCENT);
+	tests_run++;
+	printf("# Percent diff=%d\n", abs((int)diff_percent));
+	printf("# Number of bits: %d\n", no_of_bits);
+	printf("# Avg_llc_perf_miss: %lu\n", avg_llc_perf_miss);
+	printf("# Allocated cache lines: %lu\n", allocated_cache_lines);
+}
+
+static int check_results(struct resctrl_val_param *param)
+{
+	char *token_array[8], temp[512];
+	unsigned long sum_llc_perf_miss = 0;
+	int runs = 0, no_of_bits = 0;
+	FILE *fp;
+
+	printf("# Checking for pass/fail\n");
+	fp = fopen(param->filename, "r");
+	if (!fp) {
+		perror("# Cannot open file");
+
+		return errno;
+	}
+
+	while (fgets(temp, sizeof(temp), fp)) {
+		char *token = strtok(temp, ":\t");
+		int fields = 0;
+
+		while (token) {
+			token_array[fields++] = token;
+			token = strtok(NULL, ":\t");
+		}
+		/*
+		 * Discard the first value which is inaccurate due to monitoring
+		 * setup transition phase.
+		 */
+		if (runs > 0)
+			sum_llc_perf_miss += strtoul(token_array[3], NULL, 0);
+		runs++;
+	}
+
+	fclose(fp);
+	no_of_bits = count_bits(param->mask);
+
+	show_cache_info(sum_llc_perf_miss, no_of_bits, param->span);
+
+	return 0;
+}
+
+void cat_test_cleanup(void)
+{
+	remove(RESULT_FILE_NAME1);
+	remove(RESULT_FILE_NAME2);
+}
+
+int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
+{
+	unsigned long l_mask, l_mask_1;
+	int ret, pipefd[2], sibling_cpu_no;
+	char pipe_message;
+	pid_t bm_pid;
+
+	cache_size = 0;
+
+	ret = remount_resctrlfs(true);
+	if (ret)
+		return ret;
+
+	if (!validate_resctrl_feature_request("cat"))
+		return -1;
+
+	/* Get default cbm mask for L3/L2 cache */
+	ret = get_cbm_mask(cache_type);
+	if (ret)
+		return ret;
+
+	long_mask = strtoul(cbm_mask, NULL, 16);
+
+	/* Get L3/L2 cache size */
+	ret = get_cache_size(cpu_no, cache_type, &cache_size);
+	if (ret)
+		return ret;
+	printf("cache size :%lu\n", cache_size);
+
+	/* Get max number of bits from default-cabm mask */
+	count_of_bits = count_bits(long_mask);
+
+	if (n < 1 || 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);
+		return -1;
+	}
+
+	/* Get core id from same socket for running another thread */
+	sibling_cpu_no = get_core_sibling(cpu_no);
+	if (sibling_cpu_no < 0)
+		return -1;
+
+	struct resctrl_val_param param = {
+		.resctrl_val	= "cat",
+		.cpu_no		= cpu_no,
+		.mum_resctrlfs	= 0,
+		.setup		= cat_setup,
+	};
+
+	l_mask = long_mask >> n;
+	l_mask_1 = ~l_mask & long_mask;
+
+	/* 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;
+	strcpy(param.ctrlgrp, "c2");
+	strcpy(param.mongrp, "m2");
+	strcpy(param.filename, RESULT_FILE_NAME2);
+	param.mask = l_mask;
+	param.num_of_runs = 0;
+
+	if (pipe(pipefd)) {
+		perror("# Unable to create pipe");
+		return errno;
+	}
+
+	bm_pid = fork();
+
+	/* Set param values for child thread which will be allocated bitmask
+	 * with n bits
+	 */
+	if (bm_pid == 0) {
+		param.mask = l_mask_1;
+		strcpy(param.ctrlgrp, "c1");
+		strcpy(param.mongrp, "m1");
+		param.span = cache_size * n / count_of_bits;
+		strcpy(param.filename, RESULT_FILE_NAME1);
+		param.num_of_runs = 0;
+		param.cpu_no = sibling_cpu_no;
+	}
+
+	remove(param.filename);
+
+	ret = cat_val(&param);
+	if (ret)
+		return ret;
+
+	ret = check_results(&param);
+	if (ret)
+		return ret;
+
+	if (bm_pid == 0) {
+		/* Tell parent that child is ready */
+		close(pipefd[0]);
+		pipe_message = 1;
+		if (write(pipefd[1], &pipe_message, sizeof(pipe_message)) <
+		    sizeof(pipe_message)) {
+			close(pipefd[1]);
+			perror("# failed signaling parent process");
+			return errno;
+		}
+
+		close(pipefd[1]);
+		while (1)
+			;
+	} else {
+		/* Parent waits for child to be ready. */
+		close(pipefd[1]);
+		pipe_message = 0;
+		while (pipe_message != 1) {
+			if (read(pipefd[0], &pipe_message,
+				 sizeof(pipe_message)) < sizeof(pipe_message)) {
+				perror("# failed reading from child process");
+				break;
+			}
+		}
+		close(pipefd[0]);
+		kill(bm_pid, SIGKILL);
+	}
+
+	cat_test_cleanup();
+	if (bm_pid)
+		umount_resctrlfs();
+
+	return 0;
+}