greybus/tools/loopback_test.c

/*
 * Loopback test application
 *
 * Copyright 2015 Google Inc.
 * Copyright 2015 Linaro Ltd.
 *
 * Provided under the three clause BSD license found in the LICENSE file.
 */
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <poll.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#include <dirent.h>
#include <signal.h>

#define MAX_NUM_DEVICES 10
#define MAX_SYSFS_PREFIX 0x80
#define MAX_SYSFS_PATH	0x200
#define CSV_MAX_LINE	0x1000
#define SYSFS_MAX_INT	0x20
#define MAX_STR_LEN	255
#define DEFAULT_ASYNC_TIMEOUT 200000

struct dict {
	char *name;
	int type;
};

static struct dict dict[] = {
	{"ping", 2},
	{"transfer", 3},
	{"sink", 4},
	{NULL,}		/* list termination */
};

struct loopback_results {
	float latency_avg;
	uint32_t latency_max;
	uint32_t latency_min;
	uint32_t latency_jitter;

	float request_avg;
	uint32_t request_max;
	uint32_t request_min;
	uint32_t request_jitter;

	float throughput_avg;
	uint32_t throughput_max;
	uint32_t throughput_min;
	uint32_t throughput_jitter;

	float apbridge_unipro_latency_avg;
	uint32_t apbridge_unipro_latency_max;
	uint32_t apbridge_unipro_latency_min;
	uint32_t apbridge_unipro_latency_jitter;

	float gbphy_firmware_latency_avg;
	uint32_t gbphy_firmware_latency_max;
	uint32_t gbphy_firmware_latency_min;
	uint32_t gbphy_firmware_latency_jitter;

	uint32_t error;
};

struct loopback_device {
	char name[MAX_STR_LEN];
	char sysfs_entry[MAX_SYSFS_PATH];
	char debugfs_entry[MAX_SYSFS_PATH];
	struct loopback_results results;
};

struct loopback_test {
	int verbose;
	int debug;
	int raw_data_dump;
	int porcelain;
	int mask;
	int size;
	int iteration_max;
	int aggregate_output;
	int test_id;
	int device_count;
	int list_devices;
	int use_async;
	int async_timeout;
	int async_outstanding_operations;
	int us_wait;
	int file_output;
	int stop_all;
	int poll_count;
	char test_name[MAX_STR_LEN];
	char sysfs_prefix[MAX_SYSFS_PREFIX];
	char debugfs_prefix[MAX_SYSFS_PREFIX];
	struct timespec poll_timeout;
	struct loopback_device devices[MAX_NUM_DEVICES];
	struct loopback_results aggregate_results;
	struct pollfd fds[MAX_NUM_DEVICES];
};

struct loopback_test t;

/* Helper macros to calculate the aggregate results for all devices */
static inline int device_enabled(struct loopback_test *t, int dev_idx);

#define GET_MAX(field)							\
static int get_##field##_aggregate(struct loopback_test *t)		\
{									\
	uint32_t max = 0;						\
	int i;								\
	for (i = 0; i < t->device_count; i++) {				\
		if (!device_enabled(t, i))				\
			continue;					\
		if (t->devices[i].results.field > max)			\
			max = t->devices[i].results.field;		\
	}								\
	return max;							\
}									\

#define GET_MIN(field)							\
static int get_##field##_aggregate(struct loopback_test *t)		\
{									\
	uint32_t min = ~0;						\
	int i;								\
	for (i = 0; i < t->device_count; i++) {				\
		if (!device_enabled(t, i))				\
			continue;					\
		if (t->devices[i].results.field < min)			\
			min = t->devices[i].results.field;		\
	}								\
	return min;							\
}									\

#define GET_AVG(field)							\
static int get_##field##_aggregate(struct loopback_test *t)		\
{									\
	uint32_t val = 0;						\
	uint32_t count = 0;						\
	int i;								\
	for (i = 0; i < t->device_count; i++) {				\
		if (!device_enabled(t, i))				\
			continue;					\
		count++;						\
		val += t->devices[i].results.field;			\
	}								\
	if (count)							\
		val /= count;						\
	return val;							\
}									\

GET_MAX(throughput_max);
GET_MAX(request_max);
GET_MAX(latency_max);
GET_MAX(apbridge_unipro_latency_max);
GET_MAX(gbphy_firmware_latency_max);
GET_MIN(throughput_min);
GET_MIN(request_min);
GET_MIN(latency_min);
GET_MIN(apbridge_unipro_latency_min);
GET_MIN(gbphy_firmware_latency_min);
GET_AVG(throughput_avg);
GET_AVG(request_avg);
GET_AVG(latency_avg);
GET_AVG(apbridge_unipro_latency_avg);
GET_AVG(gbphy_firmware_latency_avg);

void abort(void)
{
	_exit(1);
}

void usage(void)
{
	fprintf(stderr, "Usage: loopback_test TEST [SIZE] ITERATIONS [SYSPATH] [DBGPATH]\n\n"
	"  Run TEST for a number of ITERATIONS with operation data SIZE bytes\n"
	"  TEST may be \'ping\' \'transfer\' or \'sink\'\n"
	"  SIZE indicates the size of transfer <= greybus max payload bytes\n"
	"  ITERATIONS indicates the number of times to execute TEST at SIZE bytes\n"
	"             Note if ITERATIONS is set to zero then this utility will\n"
	"             initiate an infinite (non terminating) test and exit\n"
	"             without logging any metrics data\n"
	"  SYSPATH indicates the sysfs path for the loopback greybus entries e.g.\n"
	"          /sys/bus/greybus/devices\n"
	"  DBGPATH indicates the debugfs path for the loopback greybus entries e.g.\n"
	"          /sys/kernel/debug/gb_loopback/\n"
	" Mandatory arguments\n"
	"   -t     must be one of the test names - sink, transfer or ping\n"
	"   -i     iteration count - the number of iterations to run the test over\n"
	" Optional arguments\n"
	"   -S     sysfs location - location for greybus 'endo' entires default /sys/bus/greybus/devices/\n"
	"   -D     debugfs location - location for loopback debugfs entries default /sys/kernel/debug/gb_loopback/\n"
	"   -s     size of data packet to send during test - defaults to zero\n"
	"   -m     mask - a bit mask of connections to include example: -m 8 = 4th connection -m 9 = 1st and 4th connection etc\n"
	"                 default is zero which means broadcast to all connections\n"
	"   -v     verbose output\n"
	"   -d     debug output\n"
	"   -r     raw data output - when specified the full list of latency values are included in the output CSV\n"
	"   -p     porcelain - when specified printout is in a user-friendly non-CSV format. This option suppresses writing to CSV file\n"
	"   -a     aggregate - show aggregation of all enabled devices\n"
	"   -l     list found loopback devices and exit\n"
	"   -x     Async - Enable async transfers\n"
	"   -o     Async Timeout - Timeout in uSec for async operations\n"
	"   -O     Poll loop time out in seconds(max time a test is expected to last, default: 30sec)\n"
	"   -c     Max number of outstanding operations for async operations\n"
	"   -w     Wait in uSec between operations\n"
	"   -z     Enable output to a CSV file (incompatible with -p)\n"
	"   -f     When starting new loopback test, stop currently running tests on all devices\n"
	"Examples:\n"
	"  Send 10000 transfers with a packet size of 128 bytes to all active connections\n"
	"  loopback_test -t transfer -s 128 -i 10000 -S /sys/bus/greybus/devices/ -D /sys/kernel/debug/gb_loopback/\n"
	"  loopback_test -t transfer -s 128 -i 10000 -m 0\n"
	"  Send 10000 transfers with a packet size of 128 bytes to connection 1 and 4\n"
	"  loopback_test -t transfer -s 128 -i 10000 -m 9\n"
	"  loopback_test -t ping -s 0 128 -i -S /sys/bus/greybus/devices/ -D /sys/kernel/debug/gb_loopback/\n"
	"  loopback_test -t sink -s 2030 -i 32768 -S /sys/bus/greybus/devices/ -D /sys/kernel/debug/gb_loopback/\n");
	abort();
}

static inline int device_enabled(struct loopback_test *t, int dev_idx)
{
	if (!t->mask || (t->mask & (1 << dev_idx)))
		return 1;

	return 0;
}

static void show_loopback_devices(struct loopback_test *t)
{
	int i;

	if (t->device_count == 0) {
		printf("No loopback devices.\n");
		return;
	}

	for (i = 0; i < t->device_count; i++)
		printf("device[%d] = %s\n", i, t->devices[i].name);

}

int open_sysfs(const char *sys_pfx, const char *node, int flags)
{
	int fd;
	char path[MAX_SYSFS_PATH];

	snprintf(path, sizeof(path), "%s%s", sys_pfx, node);
	fd = open(path, flags);
	if (fd < 0) {
		fprintf(stderr, "unable to open %s\n", path);
		abort();
	}
	return fd;
}

int read_sysfs_int_fd(int fd, const char *sys_pfx, const char *node)
{
	char buf[SYSFS_MAX_INT];

	if (read(fd, buf, sizeof(buf)) < 0) {
		fprintf(stderr, "unable to read from %s%s %s\n", sys_pfx, node,
			strerror(errno));
		close(fd);
		abort();
	}
	return atoi(buf);
}

float read_sysfs_float_fd(int fd, const char *sys_pfx, const char *node)
{
	char buf[SYSFS_MAX_INT];

	if (read(fd, buf, sizeof(buf)) < 0) {

		fprintf(stderr, "unable to read from %s%s %s\n", sys_pfx, node,
			strerror(errno));
		close(fd);
		abort();
	}
	return atof(buf);
}

int read_sysfs_int(const char *sys_pfx, const char *node)
{
	int fd, val;

	fd = open_sysfs(sys_pfx, node, O_RDONLY);
	val = read_sysfs_int_fd(fd, sys_pfx, node);
	close(fd);
	return val;
}

float read_sysfs_float(const char *sys_pfx, const char *node)
{
	int fd;
	float val;

	fd = open_sysfs(sys_pfx, node, O_RDONLY);
	val = read_sysfs_float_fd(fd, sys_pfx, node);
	close(fd);
	return val;
}

void write_sysfs_val(const char *sys_pfx, const char *node, int val)
{
	int fd, len;
	char buf[SYSFS_MAX_INT];

	fd = open_sysfs(sys_pfx, node, O_RDWR);
	len = snprintf(buf, sizeof(buf), "%d", val);
	if (write(fd, buf, len) < 0) {
		fprintf(stderr, "unable to write to %s%s %s\n", sys_pfx, node,
			strerror(errno));
		close(fd);
		abort();
	}
	close(fd);
}

static int get_results(struct loopback_test *t)
{
	struct loopback_device *d;
	struct loopback_results *r;
	int i;

	for (i = 0; i < t->device_count; i++) {
		if (!device_enabled(t, i))
			continue;

		d = &t->devices[i];
		r = &d->results;

		r->error = read_sysfs_int(d->sysfs_entry, "error");
		r->request_min = read_sysfs_int(d->sysfs_entry, "requests_per_second_min");
		r->request_max = read_sysfs_int(d->sysfs_entry, "requests_per_second_max");
		r->request_avg = read_sysfs_float(d->sysfs_entry, "requests_per_second_avg");

		r->latency_min = read_sysfs_int(d->sysfs_entry, "latency_min");
		r->latency_max = read_sysfs_int(d->sysfs_entry, "latency_max");
		r->latency_avg = read_sysfs_float(d->sysfs_entry, "latency_avg");

		r->throughput_min = read_sysfs_int(d->sysfs_entry, "throughput_min");
		r->throughput_max = read_sysfs_int(d->sysfs_entry, "throughput_max");
		r->throughput_avg = read_sysfs_float(d->sysfs_entry, "throughput_avg");

		r->apbridge_unipro_latency_min =
			read_sysfs_int(d->sysfs_entry, "apbridge_unipro_latency_min");
		r->apbridge_unipro_latency_max =
			read_sysfs_int(d->sysfs_entry, "apbridge_unipro_latency_max");
		r->apbridge_unipro_latency_avg =
			read_sysfs_float(d->sysfs_entry, "apbridge_unipro_latency_avg");

		r->gbphy_firmware_latency_min =
			read_sysfs_int(d->sysfs_entry, "gbphy_firmware_latency_min");
		r->gbphy_firmware_latency_max =
			read_sysfs_int(d->sysfs_entry, "gbphy_firmware_latency_max");
		r->gbphy_firmware_latency_avg =
			read_sysfs_float(d->sysfs_entry, "gbphy_firmware_latency_avg");

		r->request_jitter = r->request_max - r->request_min;
		r->latency_jitter = r->latency_max - r->latency_min;
		r->throughput_jitter = r->throughput_max - r->throughput_min;
		r->apbridge_unipro_latency_jitter =
			r->apbridge_unipro_latency_max - r->apbridge_unipro_latency_min;
		r->gbphy_firmware_latency_jitter =
			r->gbphy_firmware_latency_max - r->gbphy_firmware_latency_min;

	}

	/*calculate the aggregate results of all enabled devices */
	if (t->aggregate_output) {
		r = &t->aggregate_results;

		r->request_min = get_request_min_aggregate(t);
		r->request_max = get_request_max_aggregate(t);
		r->request_avg = get_request_avg_aggregate(t);

		r->latency_min = get_latency_min_aggregate(t);
		r->latency_max = get_latency_max_aggregate(t);
		r->latency_avg = get_latency_avg_aggregate(t);

		r->throughput_min = get_throughput_min_aggregate(t);
		r->throughput_max = get_throughput_max_aggregate(t);
		r->throughput_avg = get_throughput_avg_aggregate(t);

		r->apbridge_unipro_latency_min =
			get_apbridge_unipro_latency_min_aggregate(t);
		r->apbridge_unipro_latency_max =
			get_apbridge_unipro_latency_max_aggregate(t);
		r->apbridge_unipro_latency_avg =
			get_apbridge_unipro_latency_avg_aggregate(t);

		r->gbphy_firmware_latency_min =
			get_gbphy_firmware_latency_min_aggregate(t);
		r->gbphy_firmware_latency_max =
			get_gbphy_firmware_latency_max_aggregate(t);
		r->gbphy_firmware_latency_avg =
			get_gbphy_firmware_latency_avg_aggregate(t);

		r->request_jitter = r->request_max - r->request_min;
		r->latency_jitter = r->latency_max - r->latency_min;
		r->throughput_jitter = r->throughput_max - r->throughput_min;
		r->apbridge_unipro_latency_jitter =
			r->apbridge_unipro_latency_max - r->apbridge_unipro_latency_min;
		r->gbphy_firmware_latency_jitter =
			r->gbphy_firmware_latency_max - r->gbphy_firmware_latency_min;

	}

	return 0;
}

void log_csv_error(int len, int err)
{
	fprintf(stderr, "unable to write %d bytes to csv %s\n", len,
		strerror(err));
}

int format_output(struct loopback_test *t,
		  struct loopback_results *r,
		  const char *dev_name,
		  char *buf, int buf_len,
		  struct tm *tm)
{
	int len = 0;

	memset(buf, 0x00, buf_len);
	len = snprintf(buf, buf_len, "%u-%u-%u %u:%u:%u",
		       tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
		       tm->tm_hour, tm->tm_min, tm->tm_sec);

	if (t->porcelain) {
		len += snprintf(&buf[len], buf_len - len,
			"\n test:\t\t\t%s\n path:\t\t\t%s\n size:\t\t\t%u\n iterations:\t\t%u\n errors:\t\t%u\n async:\t\t\t%s\n",
			t->test_name,
			dev_name,
			t->size,
			t->iteration_max,
			r->error,
			t->use_async ? "Enabled" : "Disabled");

		len += snprintf(&buf[len], buf_len - len,
			" requests per-sec:\tmin=%u, max=%u, average=%f, jitter=%u\n",
			r->request_min,
			r->request_max,
			r->request_avg,
			r->request_jitter);

		len += snprintf(&buf[len], buf_len - len,
			" ap-throughput B/s:\tmin=%u max=%u average=%f jitter=%u\n",
			r->throughput_min,
			r->throughput_max,
			r->throughput_avg,
			r->throughput_jitter);
		len += snprintf(&buf[len], buf_len - len,
			" ap-latency usec:\tmin=%u max=%u average=%f jitter=%u\n",
			r->latency_min,
			r->latency_max,
			r->latency_avg,
			r->latency_jitter);
		len += snprintf(&buf[len], buf_len - len,
			" apbridge-latency usec:\tmin=%u max=%u average=%f jitter=%u\n",
			r->apbridge_unipro_latency_min,
			r->apbridge_unipro_latency_max,
			r->apbridge_unipro_latency_avg,
			r->apbridge_unipro_latency_jitter);

		len += snprintf(&buf[len], buf_len - len,
			" gbphy-latency usec:\tmin=%u max=%u average=%f jitter=%u\n",
			r->gbphy_firmware_latency_min,
			r->gbphy_firmware_latency_max,
			r->gbphy_firmware_latency_avg,
			r->gbphy_firmware_latency_jitter);

	} else {
		len += snprintf(&buf[len], buf_len - len, ",%s,%s,%u,%u,%u",
			t->test_name, dev_name, t->size, t->iteration_max,
			r->error);

		len += snprintf(&buf[len], buf_len - len, ",%u,%u,%f,%u",
			r->request_min,
			r->request_max,
			r->request_avg,
			r->request_jitter);

		len += snprintf(&buf[len], buf_len - len, ",%u,%u,%f,%u",
			r->latency_min,
			r->latency_max,
			r->latency_avg,
			r->latency_jitter);

		len += snprintf(&buf[len], buf_len - len, ",%u,%u,%f,%u",
			r->throughput_min,
			r->throughput_max,
			r->throughput_avg,
			r->throughput_jitter);

		len += snprintf(&buf[len], buf_len - len, ",%u,%u,%f,%u",
			r->apbridge_unipro_latency_min,
			r->apbridge_unipro_latency_max,
			r->apbridge_unipro_latency_avg,
			r->apbridge_unipro_latency_jitter);

		len += snprintf(&buf[len], buf_len - len, ",%u,%u,%f,%u",
			r->gbphy_firmware_latency_min,
			r->gbphy_firmware_latency_max,
			r->gbphy_firmware_latency_avg,
			r->gbphy_firmware_latency_jitter);
	}

	printf("\n%s\n", buf);

	return len;
}

static int log_results(struct loopback_test *t)
{
	int fd, i, len, ret;
	struct tm tm;
	time_t local_time;
	char file_name[MAX_SYSFS_PATH];
	char data[CSV_MAX_LINE];

	local_time = time(NULL);
	tm = *localtime(&local_time);

	/*
	 * file name will test_name_size_iteration_max.csv
	 * every time the same test with the same parameters is run we will then
	 * append to the same CSV with datestamp - representing each test
	 * dataset.
	 */
	if (t->file_output && !t->porcelain) {
		snprintf(file_name, sizeof(file_name), "%s_%d_%d.csv",
			 t->test_name, t->size, t->iteration_max);

		fd = open(file_name, O_WRONLY | O_CREAT | O_APPEND, 0644);
		if (fd < 0) {
			fprintf(stderr, "unable to open %s for appendation\n", file_name);
			abort();
		}

	}
	for (i = 0; i < t->device_count; i++) {
		if (!device_enabled(t, i))
			continue;

		len = format_output(t, &t->devices[i].results,
				    t->devices[i].name,
				    data, sizeof(data), &tm);
		if (t->file_output && !t->porcelain) {
			ret = write(fd, data, len);
			if (ret == -1)
				fprintf(stderr, "unable to write %d bytes to csv.\n", len);
		}

	}


	if (t->aggregate_output) {
		len = format_output(t, &t->aggregate_results, "aggregate",
				    data, sizeof(data), &tm);
		if (t->file_output && !t->porcelain) {
			ret = write(fd, data, len);
			if (ret == -1)
				fprintf(stderr, "unable to write %d bytes to csv.\n", len);
		}
	}

	if (t->file_output && !t->porcelain)
		close(fd);

	return 0;
}

int is_loopback_device(const char *path, const char *node)
{
	char file[MAX_SYSFS_PATH];

	snprintf(file, MAX_SYSFS_PATH, "%s%s/iteration_count", path, node);
	if (access(file, F_OK) == 0)
		return 1;
	return 0;
}

int find_loopback_devices(struct loopback_test *t)
{
	struct dirent **namelist;
	int i, n, ret;
	unsigned int dev_id;
	struct loopback_device *d;

	n = scandir(t->sysfs_prefix, &namelist, NULL, alphasort);
	if (n < 0) {
		perror("scandir");
		ret = -ENODEV;
		goto baddir;
	}

	/* Don't include '.' and '..' */
	if (n <= 2) {
		ret = -ENOMEM;
		goto done;
	}

	for (i = 0; i < n; i++) {
		ret = sscanf(namelist[i]->d_name, "gb_loopback%u", &dev_id);
		if (ret != 1)
			continue;

		if (!is_loopback_device(t->sysfs_prefix, namelist[i]->d_name))
			continue;

		if (t->device_count == MAX_NUM_DEVICES) {
			fprintf(stderr, "max number of devices reached!\n");
			break;
		}

		d = &t->devices[t->device_count++];
		snprintf(d->name, MAX_STR_LEN, "gb_loopback%u", dev_id);

		snprintf(d->sysfs_entry, MAX_SYSFS_PATH, "%s%s/",
			 t->sysfs_prefix, d->name);

		snprintf(d->debugfs_entry, MAX_SYSFS_PATH, "%sraw_latency_%s",
			 t->debugfs_prefix, d->name);

		if (t->debug)
			printf("add %s %s\n", d->sysfs_entry, d->debugfs_entry);
	}

	ret = 0;
done:
	for (i = 0; i < n; i++)
		free(namelist[i]);
	free(namelist);
baddir:
	return ret;
}

static int open_poll_files(struct loopback_test *t)
{
	struct loopback_device *dev;
	char buf[MAX_SYSFS_PATH + MAX_STR_LEN];
	char dummy;
	int fds_idx = 0;
	int i;

	for (i = 0; i < t->device_count; i++) {
		dev = &t->devices[i];

		if (!device_enabled(t, i))
			continue;

		snprintf(buf, sizeof(buf), "%s%s", dev->sysfs_entry, "iteration_count");
		t->fds[fds_idx].fd = open(buf, O_RDONLY);
		if (t->fds[fds_idx].fd < 0) {
			fprintf(stderr, "Error opening poll file!\n");
			goto err;
		}
		read(t->fds[fds_idx].fd, &dummy, 1);
		t->fds[fds_idx].events = POLLERR|POLLPRI;
		t->fds[fds_idx].revents = 0;
		fds_idx++;
	}

	t->poll_count = fds_idx;

	return 0;

err:
	for (i = 0; i < fds_idx; i++)
		close(t->fds[i].fd);

	return -1;
}

static int close_poll_files(struct loopback_test *t)
{
	int i;
	for (i = 0; i < t->poll_count; i++)
		close(t->fds[i].fd);

	return 0;
}
static int is_complete(struct loopback_test *t)
{
	int iteration_count;
	int i;

	for (i = 0; i < t->device_count; i++) {
		if (!device_enabled(t, i))
			continue;

		iteration_count = read_sysfs_int(t->devices[i].sysfs_entry,
						 "iteration_count");

		/* at least one device did not finish yet */
		if (iteration_count != t->iteration_max)
			return 0;
	}

	return 1;
}

static void stop_tests(struct loopback_test *t)
{
	int i;

	for (i = 0; i < t->device_count; i++) {
		if (!device_enabled(t, i))
			continue;
		write_sysfs_val(t->devices[i].sysfs_entry, "type", 0);
	}
}

static void handler(int sig) { /* do nothing */  }

static int wait_for_complete(struct loopback_test *t)
{
	int number_of_events = 0;
	char dummy;
	int ret;
	int i;
	struct timespec *ts = NULL;
	struct sigaction sa;
	sigset_t mask_old, mask;

	sigemptyset(&mask);
	sigemptyset(&mask_old);
	sigaddset(&mask, SIGINT);
	sigprocmask(SIG_BLOCK, &mask, &mask_old);

	sa.sa_handler = handler;
	sa.sa_flags = 0;
	sigemptyset(&sa.sa_mask);
	if (sigaction(SIGINT, &sa, NULL) == -1) {
		fprintf(stderr, "sigaction error\n");
		return -1;
	}

	if (t->poll_timeout.tv_sec != 0)
		ts = &t->poll_timeout;

	while (1) {

		ret = ppoll(t->fds, t->poll_count, ts, &mask_old);
		if (ret <= 0) {
			stop_tests(t);
			fprintf(stderr, "Poll exit with errno %d\n", errno);
			return -1;
		}

		for (i = 0; i < t->poll_count; i++) {
			if (t->fds[i].revents & POLLPRI) {
				/* Dummy read to clear the event */
				read(t->fds[i].fd, &dummy, 1);
				number_of_events++;
			}
		}

		if (number_of_events == t->poll_count)
			break;
	}

	if (!is_complete(t)) {
		fprintf(stderr, "Iteration count did not finish!\n");
		return -1;
	}

	return 0;
}

static void prepare_devices(struct loopback_test *t)
{
	int i;

	/*
	 * Cancel any running tests on enabled devices. If
	 * stop_all option is given, stop test on all devices.
	 */
	for (i = 0; i < t->device_count; i++)
		if (t->stop_all || device_enabled(t, i))
			write_sysfs_val(t->devices[i].sysfs_entry, "type", 0);


	for (i = 0; i < t->device_count; i++) {
		if (!device_enabled(t, i))
			continue;

		write_sysfs_val(t->devices[i].sysfs_entry, "us_wait",
				t->us_wait);

		/* Set operation size */
		write_sysfs_val(t->devices[i].sysfs_entry, "size", t->size);

		/* Set iterations */
		write_sysfs_val(t->devices[i].sysfs_entry, "iteration_max",
				t->iteration_max);

		if (t->use_async) {
			write_sysfs_val(t->devices[i].sysfs_entry, "async", 1);
			write_sysfs_val(t->devices[i].sysfs_entry,
					"timeout", t->async_timeout);
			write_sysfs_val(t->devices[i].sysfs_entry,
					"outstanding_operations_max",
					t->async_outstanding_operations);
		} else
			write_sysfs_val(t->devices[i].sysfs_entry, "async", 0);
	}
}

static int start(struct loopback_test *t)
{
	int i;

	/* the test starts by writing test_id to the type file. */
	for (i = 0; i < t->device_count; i++) {
		if (!device_enabled(t, i))
			continue;

		write_sysfs_val(t->devices[i].sysfs_entry, "type", t->test_id);
	}

	return 0;
}


void loopback_run(struct loopback_test *t)
{
	int i;
	int ret;

	for (i = 0; dict[i].name != NULL; i++) {
		if (strstr(dict[i].name, t->test_name))
			t->test_id = dict[i].type;
	}
	if (!t->test_id) {
		fprintf(stderr, "invalid test %s\n", t->test_name);
		usage();
		return;
	}

	prepare_devices(t);

	ret = open_poll_files(t);
	if (ret)
		goto err;

	start(t);

	ret = wait_for_complete(t);
	close_poll_files(t);
	if (ret)
		goto err;


	get_results(t);

	log_results(t);

	return;

err:
	printf("Error running test\n");
	return;
}

static int sanity_check(struct loopback_test *t)
{
	int i;

	if (t->device_count == 0) {
		fprintf(stderr, "No loopback devices found\n");
		return -1;
	}

	for (i = 0; i < MAX_NUM_DEVICES; i++) {
		if (!device_enabled(t, i))
			continue;

		if (t->mask && !strcmp(t->devices[i].name, "")) {
			fprintf(stderr, "Bad device mask %x\n", (1 << i));
			return -1;
		}

	}


	return 0;
}

int main(int argc, char *argv[])
{
	int o, ret;
	char *sysfs_prefix = "/sys/class/gb_loopback/";
	char *debugfs_prefix = "/sys/kernel/debug/gb_loopback/";

	memset(&t, 0, sizeof(t));

	while ((o = getopt(argc, argv,
			   "t:s:i:S:D:m:v::d::r::p::a::l::x::o:O:c:w:z::f::")) != -1) {
		switch (o) {
		case 't':
			snprintf(t.test_name, MAX_STR_LEN, "%s", optarg);
			break;
		case 's':
			t.size = atoi(optarg);
			break;
		case 'i':
			t.iteration_max = atoi(optarg);
			break;
		case 'S':
			snprintf(t.sysfs_prefix, MAX_SYSFS_PREFIX, "%s", optarg);
			break;
		case 'D':
			snprintf(t.debugfs_prefix, MAX_SYSFS_PREFIX, "%s", optarg);
			break;
		case 'm':
			t.mask = atol(optarg);
			break;
		case 'v':
			t.verbose = 1;
			break;
		case 'd':
			t.debug = 1;
			break;
		case 'r':
			t.raw_data_dump = 1;
			break;
		case 'p':
			t.porcelain = 1;
			break;
		case 'a':
			t.aggregate_output = 1;
			break;
		case 'l':
			t.list_devices = 1;
			break;
		case 'x':
			t.use_async = 1;
			break;
		case 'o':
			t.async_timeout = atoi(optarg);
			break;
		case 'O':
			t.poll_timeout.tv_sec = atoi(optarg);
			break;
		case 'c':
			t.async_outstanding_operations = atoi(optarg);
			break;
		case 'w':
			t.us_wait = atoi(optarg);
			break;
		case 'z':
			t.file_output = 1;
			break;
		case 'f':
			t.stop_all = 1;
			break;
		default:
			usage();
			return -EINVAL;
		}
	}

	if (!strcmp(t.sysfs_prefix, ""))
		snprintf(t.sysfs_prefix, MAX_SYSFS_PREFIX, "%s", sysfs_prefix);

	if (!strcmp(t.debugfs_prefix, ""))
		snprintf(t.debugfs_prefix, MAX_SYSFS_PREFIX, "%s", debugfs_prefix);

	ret = find_loopback_devices(&t);
	if (ret)
		return ret;
	ret = sanity_check(&t);
	if (ret)
		return ret;

	if (t.list_devices) {
		show_loopback_devices(&t);
		return 0;
	}

	if (t.test_name[0] == '\0' || t.iteration_max == 0)
		usage();

	if (t.async_timeout == 0)
		t.async_timeout = DEFAULT_ASYNC_TIMEOUT;

	loopback_run(&t);

	return 0;
}