selftests/resctrl: Remove unused measurement code

The MBM and MBA resctrl selftests run a benchmark during which
it takes measurements of read memory bandwidth via perf.
Code exists to support measurements of write memory bandwidth
but there exists no path with which this code can execute.

While code exists for write memory bandwidth measurement
there has not yet been a use case for it. Remove this unused code.
Rename relevant functions to include "read" so that it is clear
that it relates only to memory bandwidth reads, while renaming
the functions also add consistency by changing the "membw"
instances to more prevalent "mem_bw".

Signed-off-by: Reinette Chatre <[e-mail]>
Reviewed-by: Ilpo Järvinen <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/resctrl/mba_test.c

···
 {
 	int ret;
 
-	ret = initialize_mem_bw_imc();
+	ret = initialize_read_mem_bw_imc();
 	if (ret)
 		return ret;
 
···
 static int mba_measure(const struct user_params *uparams,
 		       struct resctrl_val_param *param, pid_t bm_pid)
 {
-	return measure_mem_bw(uparams, param, bm_pid, "reads");
+	return measure_read_mem_bw(uparams, param, bm_pid);
 }
 
 static bool show_mba_info(unsigned long *bw_imc, unsigned long *bw_resc)

tools/testing/selftests/resctrl/mbm_test.c

···
 {
 	int ret;
 
-	ret = initialize_mem_bw_imc();
+	ret = initialize_read_mem_bw_imc();
 	if (ret)
 		return ret;
 
···
 static int mbm_measure(const struct user_params *uparams,
 		       struct resctrl_val_param *param, pid_t bm_pid)
 {
-	return measure_mem_bw(uparams, param, bm_pid, "reads");
+	return measure_read_mem_bw(uparams, param, bm_pid);
 }
 
 static void mbm_test_cleanup(void)

tools/testing/selftests/resctrl/resctrl.h

···
 int get_domain_id(const char *resource, int cpu_no, int *domain_id);
 int mount_resctrlfs(void);
 int umount_resctrlfs(void);
-const char *get_bw_report_type(const char *bw_report);
 bool resctrl_resource_exists(const char *resource);
 bool resctrl_mon_feature_exists(const char *resource, const char *feature);
 bool resource_info_file_exists(const char *resource, const char *file);
···
 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 initialize_mem_bw_imc(void);
-int measure_mem_bw(const struct user_params *uparams,
-		   struct resctrl_val_param *param, pid_t bm_pid,
-		   const char *bw_report);
+int initialize_read_mem_bw_imc(void);
+int measure_read_mem_bw(const struct user_params *uparams,
+			struct resctrl_val_param *param, pid_t bm_pid);
 void initialize_mem_bw_resctrl(const struct resctrl_val_param *param,
 			       int domain_id);
 int resctrl_val(const struct resctrl_test *test,

tools/testing/selftests/resctrl/resctrl_val.c

···
 
 #define UNCORE_IMC		"uncore_imc"
 #define READ_FILE_NAME		"events/cas_count_read"
-#define WRITE_FILE_NAME		"events/cas_count_write"
 #define DYN_PMU_PATH		"/sys/bus/event_source/devices"
 #define SCALE			0.00006103515625
 #define MAX_IMCS		20
 #define MAX_TOKENS		5
-#define READ			0
-#define WRITE			1
 
 #define CON_MBM_LOCAL_BYTES_PATH		\
 	"%s/%s/mon_data/mon_L3_%02d/mbm_local_bytes"
···
 
 static char mbm_total_path[1024];
 static int imcs;
-static struct imc_counter_config imc_counters_config[MAX_IMCS][2];
+static struct imc_counter_config imc_counters_config[MAX_IMCS];
 static const struct resctrl_test *current_test;
 
-static void membw_initialize_perf_event_attr(int i, int j)
+static void read_mem_bw_initialize_perf_event_attr(int i)
 {
-	memset(&imc_counters_config[i][j].pe, 0,
+	memset(&imc_counters_config[i].pe, 0,
 	       sizeof(struct perf_event_attr));
-	imc_counters_config[i][j].pe.type = imc_counters_config[i][j].type;
-	imc_counters_config[i][j].pe.size = sizeof(struct perf_event_attr);
-	imc_counters_config[i][j].pe.disabled = 1;
-	imc_counters_config[i][j].pe.inherit = 1;
-	imc_counters_config[i][j].pe.exclude_guest = 0;
-	imc_counters_config[i][j].pe.config =
-		imc_counters_config[i][j].umask << 8 |
-		imc_counters_config[i][j].event;
-	imc_counters_config[i][j].pe.sample_type = PERF_SAMPLE_IDENTIFIER;
-	imc_counters_config[i][j].pe.read_format =
+	imc_counters_config[i].pe.type = imc_counters_config[i].type;
+	imc_counters_config[i].pe.size = sizeof(struct perf_event_attr);
+	imc_counters_config[i].pe.disabled = 1;
+	imc_counters_config[i].pe.inherit = 1;
+	imc_counters_config[i].pe.exclude_guest = 0;
+	imc_counters_config[i].pe.config =
+		imc_counters_config[i].umask << 8 |
+		imc_counters_config[i].event;
+	imc_counters_config[i].pe.sample_type = PERF_SAMPLE_IDENTIFIER;
+	imc_counters_config[i].pe.read_format =
 		PERF_FORMAT_TOTAL_TIME_ENABLED | PERF_FORMAT_TOTAL_TIME_RUNNING;
 }
 
-static void membw_ioctl_perf_event_ioc_reset_enable(int i, int j)
+static void read_mem_bw_ioctl_perf_event_ioc_reset_enable(int i)
 {
-	ioctl(imc_counters_config[i][j].fd, PERF_EVENT_IOC_RESET, 0);
-	ioctl(imc_counters_config[i][j].fd, PERF_EVENT_IOC_ENABLE, 0);
+	ioctl(imc_counters_config[i].fd, PERF_EVENT_IOC_RESET, 0);
+	ioctl(imc_counters_config[i].fd, PERF_EVENT_IOC_ENABLE, 0);
 }
 
-static void membw_ioctl_perf_event_ioc_disable(int i, int j)
+static void read_mem_bw_ioctl_perf_event_ioc_disable(int i)
 {
-	ioctl(imc_counters_config[i][j].fd, PERF_EVENT_IOC_DISABLE, 0);
+	ioctl(imc_counters_config[i].fd, PERF_EVENT_IOC_DISABLE, 0);
 }
 
 /*
- * get_event_and_umask:	Parse config into event and umask
+ * get_read_event_and_umask:	Parse config into event and umask
  * @cas_count_cfg:	Config
  * @count:		iMC number
- * @op:			Operation (read/write)
  */
-static void get_event_and_umask(char *cas_count_cfg, int count, bool op)
+static void get_read_event_and_umask(char *cas_count_cfg, int count)
 {
 	char *token[MAX_TOKENS];
 	int i = 0;
···
 	for (i = 0; i < MAX_TOKENS - 1; i++) {
 		if (!token[i])
 			break;
-		if (strcmp(token[i], "event") == 0) {
-			if (op == READ)
-				imc_counters_config[count][READ].event =
-				strtol(token[i + 1], NULL, 16);
-			else
-				imc_counters_config[count][WRITE].event =
-				strtol(token[i + 1], NULL, 16);
-		}
-		if (strcmp(token[i], "umask") == 0) {
-			if (op == READ)
-				imc_counters_config[count][READ].umask =
-				strtol(token[i + 1], NULL, 16);
-			else
-				imc_counters_config[count][WRITE].umask =
-				strtol(token[i + 1], NULL, 16);
-		}
+		if (strcmp(token[i], "event") == 0)
+			imc_counters_config[count].event = strtol(token[i + 1], NULL, 16);
+		if (strcmp(token[i], "umask") == 0)
+			imc_counters_config[count].umask = strtol(token[i + 1], NULL, 16);
 	}
 }
 
-static int open_perf_event(int i, int cpu_no, int j)
+static int open_perf_read_event(int i, int cpu_no)
 {
-	imc_counters_config[i][j].fd =
-		perf_event_open(&imc_counters_config[i][j].pe, -1, cpu_no, -1,
+	imc_counters_config[i].fd =
+		perf_event_open(&imc_counters_config[i].pe, -1, cpu_no, -1,
 				PERF_FLAG_FD_CLOEXEC);
 
-	if (imc_counters_config[i][j].fd == -1) {
+	if (imc_counters_config[i].fd == -1) {
 		fprintf(stderr, "Error opening leader %llx\n",
-			imc_counters_config[i][j].pe.config);
+			imc_counters_config[i].pe.config);
 
 		return -1;
 	}
···
 	return 0;
 }
 
-/* Get type and config (read and write) of an iMC counter */
+/* Get type and config of an iMC counter's read event. */
 static int read_from_imc_dir(char *imc_dir, int count)
 {
 	char cas_count_cfg[1024], imc_counter_cfg[1024], imc_counter_type[1024];
···
 
 		return -1;
 	}
-	if (fscanf(fp, "%u", &imc_counters_config[count][READ].type) <= 0) {
+	if (fscanf(fp, "%u", &imc_counters_config[count].type) <= 0) {
 		ksft_perror("Could not get iMC type");
 		fclose(fp);
 
 		return -1;
 	}
 	fclose(fp);
-
-	imc_counters_config[count][WRITE].type =
-				imc_counters_config[count][READ].type;
 
 	/* Get read config */
 	sprintf(imc_counter_cfg, "%s%s", imc_dir, READ_FILE_NAME);
···
 	}
 	fclose(fp);
 
-	get_event_and_umask(cas_count_cfg, count, READ);
-
-	/* Get write config */
-	sprintf(imc_counter_cfg, "%s%s", imc_dir, WRITE_FILE_NAME);
-	fp = fopen(imc_counter_cfg, "r");
-	if (!fp) {
-		ksft_perror("Failed to open iMC config file");
-
-		return -1;
-	}
-	if  (fscanf(fp, "%1023s", cas_count_cfg) <= 0) {
-		ksft_perror("Could not get iMC cas count write");
-		fclose(fp);
-
-		return -1;
-	}
-	fclose(fp);
-
-	get_event_and_umask(cas_count_cfg, count, WRITE);
+	get_read_event_and_umask(cas_count_cfg, count);
 
 	return 0;
 }
 
 /*
  * A system can have 'n' number of iMC (Integrated Memory Controller)
- * counters, get that 'n'. For each iMC counter get it's type and config.
- * Also, each counter has two configs, one for read and the other for write.
- * A config again has two parts, event and umask.
+ * counters, get that 'n'. Discover the properties of the available
+ * counters in support of needed performance measurement via perf.
+ * For each iMC counter get it's type and config. Also obtain each
+ * counter's event and umask for the memory read events that will be
+ * measured.
+ *
  * Enumerate all these details into an array of structures.
  *
  * Return: >= 0 on success. < 0 on failure.
···
 	return count;
 }
 
-int initialize_mem_bw_imc(void)
+int initialize_read_mem_bw_imc(void)
 {
-	int imc, j;
+	int imc;
 
 	imcs = num_of_imcs();
 	if (imcs <= 0)
 		return imcs;
 
 	/* Initialize perf_event_attr structures for all iMC's */
-	for (imc = 0; imc < imcs; imc++) {
-		for (j = 0; j < 2; j++)
-			membw_initialize_perf_event_attr(imc, j);
-	}
+	for (imc = 0; imc < imcs; imc++)
+		read_mem_bw_initialize_perf_event_attr(imc);
 
 	return 0;
 }
 
-static void perf_close_imc_mem_bw(void)
+static void perf_close_imc_read_mem_bw(void)
 {
 	int mc;
 
 	for (mc = 0; mc < imcs; mc++) {
-		if (imc_counters_config[mc][READ].fd != -1)
-			close(imc_counters_config[mc][READ].fd);
-		if (imc_counters_config[mc][WRITE].fd != -1)
-			close(imc_counters_config[mc][WRITE].fd);
+		if (imc_counters_config[mc].fd != -1)
+			close(imc_counters_config[mc].fd);
 	}
 }
 
 /*
- * perf_open_imc_mem_bw - Open perf fds for IMCs
+ * perf_open_imc_read_mem_bw - Open perf fds for IMCs
  * @cpu_no: CPU number that the benchmark PID is bound to
  *
  * Return: = 0 on success. < 0 on failure.
  */
-static int perf_open_imc_mem_bw(int cpu_no)
+static int perf_open_imc_read_mem_bw(int cpu_no)
 {
 	int imc, ret;
 
-	for (imc = 0; imc < imcs; imc++) {
-		imc_counters_config[imc][READ].fd = -1;
-		imc_counters_config[imc][WRITE].fd = -1;
-	}
+	for (imc = 0; imc < imcs; imc++)
+		imc_counters_config[imc].fd = -1;
 
 	for (imc = 0; imc < imcs; imc++) {
-		ret = open_perf_event(imc, cpu_no, READ);
-		if (ret)
-			goto close_fds;
-		ret = open_perf_event(imc, cpu_no, WRITE);
+		ret = open_perf_read_event(imc, cpu_no);
 		if (ret)
 			goto close_fds;
 	}
···
 	return 0;
 
 close_fds:
-	perf_close_imc_mem_bw();
+	perf_close_imc_read_mem_bw();
 	return -1;
 }
 
 /*
- * do_mem_bw_test - Perform memory bandwidth test
+ * do_imc_read_mem_bw_test - Perform memory bandwidth test
  *
  * Runs memory bandwidth test over one second period. Also, handles starting
  * and stopping of the IMC perf counters around the test.
  */
-static void do_imc_mem_bw_test(void)
+static void do_imc_read_mem_bw_test(void)
 {
 	int imc;
 
-	for (imc = 0; imc < imcs; imc++) {
-		membw_ioctl_perf_event_ioc_reset_enable(imc, READ);
-		membw_ioctl_perf_event_ioc_reset_enable(imc, WRITE);
-	}
+	for (imc = 0; imc < imcs; imc++)
+		read_mem_bw_ioctl_perf_event_ioc_reset_enable(imc);
 
 	sleep(1);
 
-	/* Stop counters after a second to get results (both read and write) */
-	for (imc = 0; imc < imcs; imc++) {
-		membw_ioctl_perf_event_ioc_disable(imc, READ);
-		membw_ioctl_perf_event_ioc_disable(imc, WRITE);
-	}
+	/* Stop counters after a second to get results. */
+	for (imc = 0; imc < imcs; imc++)
+		read_mem_bw_ioctl_perf_event_ioc_disable(imc);
 }
 
 /*
- * get_mem_bw_imc - Memory bandwidth as reported by iMC counters
- * @bw_report: Bandwidth report type (reads, writes)
+ * get_read_mem_bw_imc - Memory read bandwidth as reported by iMC counters
  *
- * Memory bandwidth utilized by a process on a socket can be calculated
- * using iMC counters. Perf events are used to read these counters.
+ * Memory read bandwidth utilized by a process on a socket can be calculated
+ * using iMC counters' read events. Perf events are used to read these
+ * counters.
  *
  * Return: = 0 on success. < 0 on failure.
  */
-static int get_mem_bw_imc(const char *bw_report, float *bw_imc)
+static int get_read_mem_bw_imc(float *bw_imc)
 {
-	float reads, writes, of_mul_read, of_mul_write;
+	float reads = 0, of_mul_read = 1;
 	int imc;
 
-	/* Start all iMC counters to log values (both read and write) */
-	reads = 0, writes = 0, of_mul_read = 1, of_mul_write = 1;
-
 	/*
-	 * Get results which are stored in struct type imc_counter_config
+	 * Log read event values from all iMC counters into
+	 * struct imc_counter_config.
 	 * Take overflow into consideration before calculating total bandwidth.
 	 */
 	for (imc = 0; imc < imcs; imc++) {
 		struct imc_counter_config *r =
-			&imc_counters_config[imc][READ];
-		struct imc_counter_config *w =
-			&imc_counters_config[imc][WRITE];
+			&imc_counters_config[imc];
 
 		if (read(r->fd, &r->return_value,
 			 sizeof(struct membw_read_format)) == -1) {
 			ksft_perror("Couldn't get read bandwidth through iMC");
-			return -1;
-		}
-
-		if (read(w->fd, &w->return_value,
-			 sizeof(struct membw_read_format)) == -1) {
-			ksft_perror("Couldn't get write bandwidth through iMC");
 			return -1;
 		}
 
···
 			of_mul_read = (float)r_time_enabled /
 					(float)r_time_running;
 
-		__u64 w_time_enabled = w->return_value.time_enabled;
-		__u64 w_time_running = w->return_value.time_running;
-
-		if (w_time_enabled != w_time_running)
-			of_mul_write = (float)w_time_enabled /
-					(float)w_time_running;
 		reads += r->return_value.value * of_mul_read * SCALE;
-		writes += w->return_value.value * of_mul_write * SCALE;
 	}
 
-	if (strcmp(bw_report, "reads") == 0) {
-		*bw_imc = reads;
-		return 0;
-	}
-
-	if (strcmp(bw_report, "writes") == 0) {
-		*bw_imc = writes;
-		return 0;
-	}
-
-	*bw_imc = reads + writes;
+	*bw_imc = reads;
 	return 0;
 }
 
···
 }
 
 /*
- * measure_mem_bw - Measures memory bandwidth numbers while benchmark runs
+ * measure_read_mem_bw - Measures read memory bandwidth numbers while benchmark runs
  * @uparams:		User supplied parameters
  * @param:		Parameters passed to resctrl_val()
  * @bm_pid:		PID that runs the benchmark
- * @bw_report:		Bandwidth report type (reads, writes)
  *
  * Measure memory bandwidth from resctrl and from another source which is
  * perf imc value or could be something else if perf imc event is not
  * available. Compare the two values to validate resctrl value. It takes
  * 1 sec to measure the data.
+ * resctrl does not distinguish between read and write operations so
+ * its data includes all memory operations.
  */
-int measure_mem_bw(const struct user_params *uparams,
-		   struct resctrl_val_param *param, pid_t bm_pid,
-		   const char *bw_report)
+int measure_read_mem_bw(const struct user_params *uparams,
+			struct resctrl_val_param *param, pid_t bm_pid)
 {
 	unsigned long bw_resc, bw_resc_start, bw_resc_end;
 	FILE *mem_bw_fp;
 	float bw_imc;
 	int ret;
 
-	bw_report = get_bw_report_type(bw_report);
-	if (!bw_report)
-		return -1;
-
 	mem_bw_fp = open_mem_bw_resctrl(mbm_total_path);
 	if (!mem_bw_fp)
 		return -1;
 
-	ret = perf_open_imc_mem_bw(uparams->cpu);
+	ret = perf_open_imc_read_mem_bw(uparams->cpu);
 	if (ret < 0)
 		goto close_fp;
 
···
 
 	rewind(mem_bw_fp);
 
-	do_imc_mem_bw_test();
+	do_imc_read_mem_bw_test();
 
 	ret = get_mem_bw_resctrl(mem_bw_fp, &bw_resc_end);
 	if (ret < 0)
 		goto close_imc;
 
-	ret = get_mem_bw_imc(bw_report, &bw_imc);
+	ret = get_read_mem_bw_imc(&bw_imc);
 	if (ret < 0)
 		goto close_imc;
 
-	perf_close_imc_mem_bw();
+	perf_close_imc_read_mem_bw();
 	fclose(mem_bw_fp);
 
 	bw_resc = (bw_resc_end - bw_resc_start) / MB;
···
 	return print_results_bw(param->filename, bm_pid, bw_imc, bw_resc);
 
 close_imc:
-	perf_close_imc_mem_bw();
+	perf_close_imc_read_mem_bw();
 close_fp:
 	fclose(mem_bw_fp);
 	return ret;

tools/testing/selftests/resctrl/resctrlfs.c

···
 	return 0;
 }
 
-const char *get_bw_report_type(const char *bw_report)
-{
-	if (strcmp(bw_report, "reads") == 0)
-		return bw_report;
-	if (strcmp(bw_report, "writes") == 0)
-		return bw_report;
-	if (strcmp(bw_report, "nt-writes") == 0) {
-		return "writes";
-	}
-	if (strcmp(bw_report, "total") == 0)
-		return bw_report;
-
-	fprintf(stderr, "Requested iMC bandwidth report type unavailable\n");
-
-	return NULL;
-}
-
 int perf_event_open(struct perf_event_attr *hw_event, pid_t pid, int cpu,
 		    int group_fd, unsigned long flags)
 {