path: root/bin/rtspin.c

#include <sys/time.h>

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <assert.h>


#include "litmus.h"
#include "common.h"


static double cputime()
{
	struct timespec ts;
	int err;
	err = clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts);
	if (err != 0)
		perror("clock_gettime");
	return (ts.tv_sec + 1E-9 * ts.tv_nsec);
}

static double wctime()
{
	struct timeval tv;
	gettimeofday(&tv, NULL);
	return (tv.tv_sec + 1E-6 * tv.tv_usec);
}

static void usage(char *error) {
	fprintf(stderr, "Error: %s\n", error);
	fprintf(stderr,
		"Usage:\n"
		"	rt_spin [COMMON-OPTS] WCET PERIOD DURATION\n"
		"	rt_spin [COMMON-OPTS] -f FILE [-o COLUMN] WCET PERIOD\n"
		"	rt_spin -l\n"
		"\n"
		"COMMON-OPTS = [-w] [-p PARTITION] [-c CLASS] [-s SCALE]\n"
		"\n"
		"WCET and PERIOD are milliseconds, DURATION is seconds.\n");
	exit(EXIT_FAILURE);
}

/*
 * returns the character that made processing stop, newline or EOF
 */
static int skip_to_next_line(FILE *fstream)
{
	int ch;
	for (ch = fgetc(fstream); ch != EOF && ch != '\n'; ch = fgetc(fstream));
	return ch;
}

static void skip_comments(FILE *fstream)
{
	int ch;
	for (ch = fgetc(fstream); ch == '#'; ch = fgetc(fstream))
		skip_to_next_line(fstream);
	ungetc(ch, fstream);
}

static void get_exec_times(const char *file, const int column,
			   int *num_jobs,    double **exec_times)
{
	FILE *fstream;
	int  cur_job, cur_col, ch;
	*num_jobs = 0;

	fstream = fopen(file, "r");
	if (!fstream)
		bail_out("could not open execution time file");

	/* figure out the number of jobs */
	do {
		skip_comments(fstream);
		ch = skip_to_next_line(fstream);
		if (ch != EOF)
			++(*num_jobs);
	} while (ch != EOF);

	if (-1 == fseek(fstream, 0L, SEEK_SET))
		bail_out("rewinding file failed");

	/* allocate space for exec times */
	*exec_times = calloc(*num_jobs, sizeof(*exec_times));
	if (!*exec_times)
		bail_out("couldn't allocate memory");

	for (cur_job = 0; cur_job < *num_jobs && !feof(fstream); ++cur_job) {

		skip_comments(fstream);

		for (cur_col = 1; cur_col < column; ++cur_col) {
			/* discard input until we get to the column we want */
			fscanf(fstream, "%*s,");
		}

		/* get the desired exec. time */
		if (1 != fscanf(fstream, "%lf", (*exec_times)+cur_job)) {
			fprintf(stderr, "invalid execution time near line %d\n",
					cur_job);
			exit(EXIT_FAILURE);
		}

		skip_to_next_line(fstream);
	}

	assert(cur_job == *num_jobs);
	fclose(fstream);
}

#define NUMS 4096
static int num[NUMS];
static double loop_length = 1.0;
static char* progname;

static int loop_once(void)
{
	int i, j = 0;
	for (i = 0; i < NUMS; i++)
		j += num[i]++;
	return j;
}

static int loop_for(double exec_time, double emergency_exit)
{
	double t = 0;
	int tmp = 0;
/*	while (t + loop_length < exec_time) {
		tmp += loop_once();
		t += loop_length;
	}
*/
	double start = cputime();
	double now = cputime();
	while (now + loop_length < start + exec_time) {
		tmp += loop_once();
		t += loop_length;
		now = cputime();
		if (emergency_exit && wctime() > emergency_exit) {
			/* Oops --- this should only be possible if the execution time tracking
			 * is broken in the LITMUS^RT kernel. */
			fprintf(stderr, "!!! rtspin/%d emergency exit!\n", getpid());
			fprintf(stderr, "Something is seriously wrong! Do not ignore this.\n");
			break;
		}
	}

	return tmp;
}

static void fine_tune(double interval)
{
	double start, end, delta;

	start = wctime();
	loop_for(interval, 0);
	end = wctime();
	delta = (end - start - interval) / interval;
	if (delta != 0)
		loop_length = loop_length / (1 - delta);
}

static void configure_loop(void)
{
	double start;

	/* prime cache */
	loop_once();
	loop_once();
	loop_once();

	/* measure */
	start = wctime();
	loop_once(); /* hope we didn't get preempted  */
	loop_length = wctime();
	loop_length -= start;

	/* fine tune */
	fine_tune(0.1);
	fine_tune(0.1);
	fine_tune(0.1);
}

static void show_loop_length(void)
{
	printf("%s/%d: loop_length=%f (%ldus)\n",
	       progname, getpid(), loop_length,
	       (long) (loop_length * 1000000));
}

static void debug_delay_loop(void)
{
	double start, end, delay;
	show_loop_length();
	while (1) {
		for (delay = 0.5; delay > 0.01; delay -= 0.01) {
			start = wctime();
			loop_for(delay, 0);
			end = wctime();
			printf("%6.4fs: looped for %10.8fs, delta=%11.8fs, error=%7.4f%%\n",
			       delay,
			       end - start,
			       end - start - delay,
			       100 * (end - start - delay) / delay);
		}
	}
}

static int job(double exec_time, double program_end)
{
	if (wctime() > program_end)
		return 0;
	else {
		loop_for(exec_time, program_end + 1);
		sleep_next_period();
		return 1;
	}
}

#define OPTSTR "p:c:wld:veo:f:s:"

int main(int argc, char** argv) 
{
	int ret;
	lt_t wcet;
	lt_t period;
	double wcet_ms, period_ms;
	int migrate = 0;
	int cpu = 0;
	int opt;
	int wait = 0;
	int test_loop = 0;
	int skip_config = 0;
	int verbose = 0;
	int column = 1;
	const char *file = NULL;
	int want_enforcement = 0;
	double duration = 0, start;
	double *exec_times = NULL;
	double scale = 1.0;
	task_class_t class = RT_CLASS_HARD;
	int cur_job, num_jobs;

	progname = argv[0];

	while ((opt = getopt(argc, argv, OPTSTR)) != -1) {
		switch (opt) {
		case 'w':
			wait = 1;
			break;
		case 'p':
			cpu = atoi(optarg);
			migrate = 1;
			break;
		case 'c':
			class = str2class(optarg);
			if (class == -1)
				usage("Unknown task class.");
			break;
		case 'e':
			want_enforcement = 1;
			break;
		case 'l':
			test_loop = 1;
			break;
		case 'd':
			/* manually configure delay per loop iteration 
			 * unit: microseconds */
			loop_length = atof(optarg) / 1000000;
			skip_config = 1;
			break;
		case 'v':
			verbose = 1;
			break;
		case 'o':
			column = atoi(optarg);
			break;
		case 'f':
			file = optarg;
			break;
		case 's':
			scale = atof(optarg);
			break;
		case ':':
			usage("Argument missing.");
			break;
		case '?':
		default:
			usage("Bad argument.");
			break;
		}
	}


	if (!skip_config)
		configure_loop();

	if (test_loop) {
		debug_delay_loop();
		return 0;
	}

	if (file) {
		get_exec_times(file, column, &num_jobs, &exec_times);

		if (argc - optind < 2)
			usage("Arguments missing.");

		for (cur_job = 0; cur_job < num_jobs; ++cur_job) {
			/* convert the execution time to seconds */
			duration += exec_times[cur_job] * 0.001;
		}
	} else {
		/*
		 * if we're not reading from the CSV file, then we need
		 * three parameters
		 */
		if (argc - optind < 3)
			usage("Arguments missing.");
	}

	wcet_ms   = atof(argv[optind + 0]);
	period_ms = atof(argv[optind + 1]);

	wcet   = wcet_ms * __NS_PER_MS;
	period = period_ms * __NS_PER_MS;
	if (wcet <= 0)
		usage("The worst-case execution time must be a "
				"positive number.");
	if (period <= 0)
		usage("The period must be a positive number.");
	if (!file && wcet > period) {
		usage("The worst-case execution time must not "
				"exceed the period.");
	}

	if (!file)
		duration  = atof(argv[optind + 2]);
	else if (file && num_jobs > 1)
		duration += period_ms * 0.001 * (num_jobs - 1);

	if (migrate) {
		ret = be_migrate_to(cpu);
		if (ret < 0)
			bail_out("could not migrate to target partition");
	}

	ret = sporadic_task_ns(wcet, period, 0, cpu, class,
			       want_enforcement ? PRECISE_ENFORCEMENT
			                        : NO_ENFORCEMENT,
			       migrate);
	if (ret < 0)
		bail_out("could not setup rt task params");

	if (verbose)
		show_loop_length();

	init_litmus();

	ret = task_mode(LITMUS_RT_TASK);
	if (ret != 0)
		bail_out("could not become RT task");

	if (wait) {
		ret = wait_for_ts_release();
		if (ret != 0)
			bail_out("wait_for_ts_release()");
	}

	start = wctime();

	if (file) {
		/* use times read from the CSV file */
		for (cur_job = 0; cur_job < num_jobs; ++cur_job) {
			/* convert job's length to seconds */
			job(exec_times[cur_job] * 0.001 * scale,
					start + duration);
		}
	} else {
		/* conver to seconds and scale */
		while (job(wcet_ms * 0.001 * scale, start + duration));
	}

	ret = task_mode(BACKGROUND_TASK);
	if (ret != 0)
		bail_out("could not become regular task (huh?)");

	if (file)
		free(exec_times);

	return 0;
}