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#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.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);
}
void usage(char *error) {
fprintf(stderr, "Error: %s\n", error);
fprintf(stderr,
"Usage: rt_spin [-w] [-p PARTITION] [-c CLASS] WCET PERIOD DURATION\n"
" rt_spin -l\n");
exit(1);
}
#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 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();
}
return tmp;
}
static void fine_tune(double interval)
{
double start, end, delta;
start = wctime();
loop_for(interval);
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);
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)
{
loop_for(exec_time);
sleep_next_period();
return 0;
}
#define OPTSTR "p:c:wld:ve"
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 want_enforcement = 0;
double duration, start;
task_class_t class = RT_CLASS_HARD;
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 ':':
usage("Argument missing.");
break;
case '?':
default:
usage("Bad argument.");
break;
}
}
if (!skip_config)
configure_loop();
if (test_loop) {
debug_delay_loop();
return 0;
}
if (argc - optind < 3)
usage("Arguments missing.");
wcet_ms = atof(argv[optind + 0]);
period_ms = atof(argv[optind + 1]);
duration = atof(argv[optind + 2]);
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 (wcet > period) {
usage("The worst-case execution time must not "
"exceed the period.");
}
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,
LITMUS_FP_ZERO, LITMUS_FP_ZERO,
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();
while (start + duration > wctime()) {
job(wcet_ms * 0.0009); /* 90% wcet, in seconds */
}
return 0;
}
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