4 files changed, 139 insertions, 199 deletions

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
index 36e62baebf4f..b79916069788 100644
--- a/tools/testing/selftests/resctrl/cat_test.c
+++ b/tools/testing/selftests/resctrl/cat_test.c
@@ -11,65 +11,70 @@
 #include "resctrl.h"
 #include <unistd.h>
 
-#define RESULT_FILE_NAME1	"result_cat1"
-#define RESULT_FILE_NAME2	"result_cat2"
+#define RESULT_FILE_NAME	"result_cat"
 #define NUM_OF_RUNS		5
-#define MAX_DIFF_PERCENT	4
-#define MAX_DIFF		1000000
 
 /*
- * Change schemata. Write schemata to specified
- * con_mon grp, mon_grp in resctrl FS.
- * Run 5 times in order to get average values.
+ * Minimum difference in LLC misses between a test with n+1 bits CBM to the
+ * test with n bits is MIN_DIFF_PERCENT_PER_BIT * (n - 1). With e.g. 5 vs 4
+ * bits in the CBM mask, the minimum difference must be at least
+ * MIN_DIFF_PERCENT_PER_BIT * (4 - 1) = 3 percent.
+ *
+ * The relationship between number of used CBM bits and difference in LLC
+ * misses is not expected to be linear. With a small number of bits, the
+ * margin is smaller than with larger number of bits. For selftest purposes,
+ * however, linear approach is enough because ultimately only pass/fail
+ * decision has to be made and distinction between strong and stronger
+ * signal is irrelevant.
  */
-static int cat_setup(struct resctrl_val_param *p)
-{
-	char schemata[64];
-	int ret = 0;
-
-	/* Run NUM_OF_RUNS times */
-	if (p->num_of_runs >= NUM_OF_RUNS)
-		return END_OF_TESTS;
-
-	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;
-}
+#define MIN_DIFF_PERCENT_PER_BIT	1UL
 
 static int show_results_info(__u64 sum_llc_val, int no_of_bits,
-			     unsigned long cache_span, unsigned long max_diff,
-			     unsigned long max_diff_percent, unsigned long num_of_runs,
-			     bool platform)
+			     unsigned long cache_span,
+			     unsigned long min_diff_percent,
+			     unsigned long num_of_runs, bool platform,
+			     __s64 *prev_avg_llc_val)
 {
 	__u64 avg_llc_val = 0;
-	float diff_percent;
-	int ret;
+	float avg_diff;
+	int ret = 0;
 
 	avg_llc_val = sum_llc_val / num_of_runs;
-	diff_percent = ((float)cache_span - avg_llc_val) / cache_span * 100;
+	if (*prev_avg_llc_val) {
+		float delta = (__s64)(avg_llc_val - *prev_avg_llc_val);
 
-	ret = platform && abs((int)diff_percent) > max_diff_percent;
+		avg_diff = delta / *prev_avg_llc_val;
+		ret = platform && (avg_diff * 100) < (float)min_diff_percent;
 
-	ksft_print_msg("%s Check cache miss rate within %lu%%\n",
-		       ret ? "Fail:" : "Pass:", max_diff_percent);
+		ksft_print_msg("%s Check cache miss rate changed more than %.1f%%\n",
+			       ret ? "Fail:" : "Pass:", (float)min_diff_percent);
 
-	ksft_print_msg("Percent diff=%d\n", abs((int)diff_percent));
+		ksft_print_msg("Percent diff=%.1f\n", avg_diff * 100);
+	}
+	*prev_avg_llc_val = avg_llc_val;
 
 	show_cache_info(no_of_bits, avg_llc_val, cache_span, true);
 
 	return ret;
 }
 
-static int check_results(struct resctrl_val_param *param, size_t span)
+/* Remove the highest bit from CBM */
+static unsigned long next_mask(unsigned long current_mask)
+{
+	return current_mask & (current_mask >> 1);
+}
+
+static int check_results(struct resctrl_val_param *param, const char *cache_type,
+			 unsigned long cache_total_size, unsigned long full_cache_mask,
+			 unsigned long current_mask)
 {
 	char *token_array[8], temp[512];
-	int runs = 0, no_of_bits = 0;
 	__u64 sum_llc_perf_miss = 0;
+	__s64 prev_avg_llc_val = 0;
+	unsigned long alloc_size;
+	int runs = 0;
+	int fail = 0;
+	int ret;
 	FILE *fp;
 
 	ksft_print_msg("Checking for pass/fail\n");
@@ -83,49 +88,78 @@ static int check_results(struct resctrl_val_param *param, size_t span)
 	while (fgets(temp, sizeof(temp), fp)) {
 		char *token = strtok(temp, ":\t");
 		int fields = 0;
+		int bits;
 
 		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 += strtoull(token_array[3], NULL, 0);
+
+		sum_llc_perf_miss += strtoull(token_array[3], NULL, 0);
 		runs++;
+
+		if (runs < NUM_OF_RUNS)
+			continue;
+
+		if (!current_mask) {
+			ksft_print_msg("Unexpected empty cache mask\n");
+			break;
+		}
+
+		alloc_size = cache_portion_size(cache_total_size, current_mask, full_cache_mask);
+
+		bits = count_bits(current_mask);
+
+		ret = show_results_info(sum_llc_perf_miss, bits,
+					alloc_size / 64,
+					MIN_DIFF_PERCENT_PER_BIT * (bits - 1),
+					runs, get_vendor() == ARCH_INTEL,
+					&prev_avg_llc_val);
+		if (ret)
+			fail = 1;
+
+		runs = 0;
+		sum_llc_perf_miss = 0;
+		current_mask = next_mask(current_mask);
 	}
 
 	fclose(fp);
-	no_of_bits = count_bits(param->mask);
 
-	return show_results_info(sum_llc_perf_miss, no_of_bits, span / 64,
-				 MAX_DIFF, MAX_DIFF_PERCENT, runs - 1,
-				 get_vendor() == ARCH_INTEL);
+	return fail;
 }
 
 void cat_test_cleanup(void)
 {
-	remove(RESULT_FILE_NAME1);
-	remove(RESULT_FILE_NAME2);
+	remove(RESULT_FILE_NAME);
 }
 
 /*
  * cat_test - Execute CAT benchmark and measure cache misses
  * @param:		Parameters passed to cat_test()
  * @span:		Buffer size for the benchmark
+ * @current_mask	Start mask for the first iteration
+ *
+ * Run CAT selftest by varying the allocated cache portion and comparing the
+ * impact on cache misses (the result analysis is done in check_results()
+ * and show_results_info(), not in this function).
+ *
+ * One bit is removed from the CAT allocation bit mask (in current_mask) for
+ * each subsequent test which keeps reducing the size of the allocated cache
+ * portion. A single test flushes the buffer, reads it to warm up the cache,
+ * and reads the buffer again. The cache misses are measured during the last
+ * read pass.
  *
  * Return:		0 when the test was run, < 0 on error.
  */
-static int cat_test(struct resctrl_val_param *param, size_t span)
+static int cat_test(struct resctrl_val_param *param, size_t span, unsigned long current_mask)
 {
-	int memflush = 1, operation = 0, ret = 0;
 	char *resctrl_val = param->resctrl_val;
 	struct perf_event_read pe_read;
 	struct perf_event_attr pea;
+	unsigned char *buf;
+	char schemata[64];
+	int ret, i, pe_fd;
 	pid_t bm_pid;
-	int pe_fd;
 
 	if (strcmp(param->filename, "") == 0)
 		sprintf(param->filename, "stdio");
@@ -149,48 +183,55 @@ static int cat_test(struct resctrl_val_param *param, size_t span)
 	if (pe_fd < 0)
 		return pe_fd;
 
-	/* Test runs until the callback setup() tells the test to stop. */
-	while (1) {
-		ret = param->setup(param);
-		if (ret == END_OF_TESTS) {
-			ret = 0;
-			break;
-		}
-		if (ret < 0)
-			break;
+	buf = alloc_buffer(span, 1);
+	if (!buf) {
+		ret = -1;
+		goto pe_close;
+	}
 
-		ret = perf_event_reset_enable(pe_fd);
+	while (current_mask) {
+		snprintf(schemata, sizeof(schemata), "%lx", param->mask & ~current_mask);
+		ret = write_schemata("", schemata, param->cpu_no, param->resctrl_val);
 		if (ret)
-			goto pe_close;
+			goto free_buf;
+		snprintf(schemata, sizeof(schemata), "%lx", current_mask);
+		ret = write_schemata(param->ctrlgrp, schemata, param->cpu_no, param->resctrl_val);
+		if (ret)
+			goto free_buf;
 
-		if (run_fill_buf(span, memflush, operation, true)) {
-			fprintf(stderr, "Error-running fill buffer\n");
-			ret = -1;
-			goto pe_close;
-		}
+		for (i = 0; i < NUM_OF_RUNS; i++) {
+			mem_flush(buf, span);
+			fill_cache_read(buf, span, true);
 
-		sleep(1);
-		ret = perf_event_measure(pe_fd, &pe_read, param->filename, bm_pid);
-		if (ret)
-			goto pe_close;
-	}
+			ret = perf_event_reset_enable(pe_fd);
+			if (ret)
+				goto free_buf;
 
-	return ret;
+			fill_cache_read(buf, span, true);
 
+			ret = perf_event_measure(pe_fd, &pe_read, param->filename, bm_pid);
+			if (ret)
+				goto free_buf;
+		}
+		current_mask = next_mask(current_mask);
+	}
+
+free_buf:
+	free(buf);
 pe_close:
 	close(pe_fd);
+
 	return ret;
 }
 
 int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
 {
-	unsigned long full_cache_mask, long_mask;
-	unsigned long l_mask, l_mask_1;
-	int ret, pipefd[2], sibling_cpu_no;
+	unsigned long long_mask, start_mask, full_cache_mask;
 	unsigned long cache_total_size = 0;
+	unsigned int start;
 	int count_of_bits;
-	char pipe_message;
 	size_t span;
+	int ret;
 
 	ret = get_full_cbm(cache_type, &full_cache_mask);
 	if (ret)
@@ -206,7 +247,7 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
 		return ret;
 	ksft_print_msg("Cache size :%lu\n", cache_total_size);
 
-	count_of_bits = count_bits(long_mask);
+	count_of_bits = count_contiguous_bits(long_mask, &start);
 
 	if (!n)
 		n = count_of_bits / 2;
@@ -217,88 +258,26 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
 			       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;
+	start_mask = create_bit_mask(start, n);
 
 	struct resctrl_val_param param = {
 		.resctrl_val	= CAT_STR,
 		.cpu_no		= cpu_no,
-		.setup		= cat_setup,
+		.ctrlgrp	= "c1",
+		.filename	= RESULT_FILE_NAME,
+		.num_of_runs	= 0,
 	};
-
-	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
-	 */
-	span = cache_portion_size(cache_total_size, l_mask, full_cache_mask);
-	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)) {
-		ksft_perror("Unable to create pipe");
-		return -1;
-	}
-
-	fflush(stdout);
-	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");
-		span = cache_portion_size(cache_total_size, l_mask_1, full_cache_mask);
-		strcpy(param.filename, RESULT_FILE_NAME1);
-		param.num_of_runs = 0;
-		param.cpu_no = sibling_cpu_no;
-	}
+	param.mask = long_mask;
+	span = cache_portion_size(cache_total_size, start_mask, full_cache_mask);
 
 	remove(param.filename);
 
-	ret = cat_test(&param, span);
-	if (ret == 0)
-		ret = check_results(&param, span);
-
-	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))
-			/*
-			 * Just print the error message.
-			 * Let while(1) run and wait for itself to be killed.
-			 */
-			ksft_perror("Failed signaling parent process");
-
-		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)) {
-				ksft_perror("Failed reading from child process");
-				break;
-			}
-		}
-		close(pipefd[0]);
-		kill(bm_pid, SIGKILL);
-	}
+	ret = cat_test(&param, span, start_mask);
+	if (ret)
+		goto out;
 
+	ret = check_results(&param, cache_type, cache_total_size, full_cache_mask, start_mask);
+out:
 	cat_test_cleanup();
 
 	return ret;
diff --git a/tools/testing/selftests/resctrl/fill_buf.c b/tools/testing/selftests/resctrl/fill_buf.c
index 93a3d408339c..ae120f1735c0 100644
--- a/tools/testing/selftests/resctrl/fill_buf.c
+++ b/tools/testing/selftests/resctrl/fill_buf.c
@@ -38,7 +38,7 @@ static void cl_flush(void *p)
 #endif
 }
 
-static void mem_flush(unsigned char *buf, size_t buf_size)
+void mem_flush(unsigned char *buf, size_t buf_size)
 {
 	unsigned char *cp = buf;
 	size_t i = 0;
@@ -100,7 +100,7 @@ static void fill_one_span_write(unsigned char *buf, size_t buf_size)
 	}
 }
 
-static void fill_cache_read(unsigned char *buf, size_t buf_size, bool once)
+void fill_cache_read(unsigned char *buf, size_t buf_size, bool once)
 {
 	int ret = 0;
 
@@ -123,7 +123,7 @@ static void fill_cache_write(unsigned char *buf, size_t buf_size, bool once)
 	}
 }
 
-static unsigned char *alloc_buffer(size_t buf_size, int memflush)
+unsigned char *alloc_buffer(size_t buf_size, int memflush)
 {
 	void *buf = NULL;
 	uint64_t *p64;
diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
index 5b9bea505120..4f040e999eea 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -105,6 +105,9 @@ int write_bm_pid_to_resctrl(pid_t bm_pid, char *ctrlgrp, char *mongrp,
 			    char *resctrl_val);
 int perf_event_open(struct perf_event_attr *hw_event, pid_t pid, int cpu,
 		    int group_fd, unsigned long flags);
+unsigned char *alloc_buffer(size_t buf_size, int memflush);
+void mem_flush(unsigned char *buf, size_t buf_size);
+void fill_cache_read(unsigned char *buf, size_t buf_size, bool once);
 int run_fill_buf(size_t buf_size, int memflush, int op, bool once);
 int resctrl_val(const char * const *benchmark_cmd, struct resctrl_val_param *param);
 int mbm_bw_change(int cpu_no, const char * const *benchmark_cmd);
@@ -113,6 +116,7 @@ void mbm_test_cleanup(void);
 int mba_schemata_change(int cpu_no, const char * const *benchmark_cmd);
 void mba_test_cleanup(void);
 unsigned long create_bit_mask(unsigned int start, unsigned int len);
+unsigned int count_contiguous_bits(unsigned long val, unsigned int *start);
 int get_full_cbm(const char *cache_type, unsigned long *mask);
 int get_mask_no_shareable(const char *cache_type, unsigned long *mask);
 int get_cache_size(int cpu_no, const char *cache_type, unsigned long *cache_size);
@@ -124,7 +128,6 @@ int cat_perf_miss_val(int cpu_no, int no_of_bits, char *cache_type);
 int cmt_resctrl_val(int cpu_no, int n, const char * const *benchmark_cmd);
 unsigned int count_bits(unsigned long n);
 void cmt_test_cleanup(void);
-int get_core_sibling(int cpu_no);
 
 void perf_event_attr_initialize(struct perf_event_attr *pea, __u64 config);
 void perf_event_initialize_read_format(struct perf_event_read *pe_read);
diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
index 3ec09688cfc3..846281e429ca 100644
--- a/tools/testing/selftests/resctrl/resctrlfs.c
+++ b/tools/testing/selftests/resctrl/resctrlfs.c
@@ -245,7 +245,7 @@ unsigned long create_bit_mask(unsigned int start, unsigned int len)
  *
  * Return:	The length of the contiguous bits in the longest train of bits
  */
-static unsigned int count_contiguous_bits(unsigned long val, unsigned int *start)
+unsigned int count_contiguous_bits(unsigned long val, unsigned int *start)
 {
 	unsigned long last_val;
 	unsigned int count = 0;
@@ -344,48 +344,6 @@ int get_mask_no_shareable(const char *cache_type, unsigned long *mask)
 }
 
 /*
- * get_core_sibling - Get sibling core id from the same socket for given CPU
- * @cpu_no:	CPU number
- *
- * Return:	> 0 on success, < 0 on failure.
- */
-int get_core_sibling(int cpu_no)
-{
-	char core_siblings_path[1024], cpu_list_str[64];
-	int sibling_cpu_no = -1;
-	FILE *fp;
-
-	sprintf(core_siblings_path, "%s%d/topology/core_siblings_list",
-		CORE_SIBLINGS_PATH, cpu_no);
-
-	fp = fopen(core_siblings_path, "r");
-	if (!fp) {
-		ksft_perror("Failed to open core siblings path");
-
-		return -1;
-	}
-	if (fscanf(fp, "%s", cpu_list_str) <= 0) {
-		ksft_perror("Could not get core_siblings list");
-		fclose(fp);
-
-		return -1;
-	}
-	fclose(fp);
-
-	char *token = strtok(cpu_list_str, "-,");
-
-	while (token) {
-		sibling_cpu_no = atoi(token);
-		/* Skipping core 0 as we don't want to run test on core 0 */
-		if (sibling_cpu_no != 0 && sibling_cpu_no != cpu_no)
-			break;
-		token = strtok(NULL, "-,");
-	}
-
-	return sibling_cpu_no;
-}
-
-/*
  * taskset_benchmark - Taskset PID (i.e. benchmark) to a specified cpu
  * @bm_pid:	PID that should be binded
  * @cpu_no:	CPU number at which the PID would be binded