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32 * $FreeBSD: src/tools/regression/p1003_1b/fifo.c,v 1.1 2000/02/16 14:28:40 dufault Exp $
33 * $DragonFly: src/tools/regression/p1003_1b/fifo.c,v 1.3 2007/06/26 23:30:05 josepht Exp $
41 #include <sys/types.h>
44 #include <sys/sched.h>
48 #define CAN_USE_ALARMS
57 /* Fifo: Verify that fifo and round-robin scheduling seem to work.
60 * 1. That sched_rr_get_interval seems to work;
61 * 2. That FIFO scheduling doesn't seeem to be round-robin;
62 * 3. That round-robin scheduling seems to work.
66 static void tidyup(void)
73 tvsub(const struct timeval *a, const struct timeval *b)
78 sdiff = a->tv_sec - b->tv_sec;
79 udiff = a->tv_usec - b->tv_usec;
81 return (double)(sdiff * 1000000 + udiff) / 1e6;
84 int fifo(int argc, char *argv[])
87 volatile long *p, pid;
89 struct sched_param fifo_param;
90 struct timespec interval;
92 struct timeval ranat[MAX_RANAT];
95 static struct itimerval itimerval;
98 /* What is the round robin interval?
101 if (sched_rr_get_interval(0, &interval) == -1) {
102 perror("sched_rr_get_interval");
106 #ifdef CAN_USE_ALARMS
107 signal(SIGALRM, tick);
110 fifo_param.sched_priority = 1;
112 p = (long *)mmap(0, sizeof(*p),
113 PROT_READ|PROT_WRITE, MAP_ANON|MAP_SHARED|MAP_INHERIT, -1, 0);
120 if (sched_setscheduler(0, SCHED_FIFO, &fifo_param) == -1)
122 perror("sched_setscheduler");
128 if ((child = fork()) == 0)
130 /* Child process. Just keep setting the pointer to our
131 * PID. The parent will kill us when it wants to.
146 #ifdef CAN_USE_ALARMS
147 /* Set an alarm for 250 times the round-robin interval.
148 * Then we will verify that a similar priority process
149 * will not run when we are using the FIFO scheduler.
151 itimerval.it_value.tv_usec = interval.tv_nsec / (1000 / 250);
153 itimerval.it_value.tv_sec = itimerval.it_value.tv_usec / 1000000;
154 itimerval.it_value.tv_usec %= 1000000;
157 if (setitimer(ITIMER_REAL, &itimerval, 0) == -1) {
164 gettimeofday(ranat, 0);
166 while (!ticked && i < MAX_RANAT)
168 gettimeofday(ranat + i, 0);
178 "SCHED_FIFO had erroneous context switches:\n");
179 for (j = 1; j < i; j++) {
180 fprintf(stderr, "%d %g\n", j,
181 tvsub(ranat + j, ranat + j - 1));
186 /* Switch to the round robin scheduler and the child
187 * should run within twice the interval.
189 if (sched_setscheduler(child, SCHED_RR, &fifo_param) == -1 ||
190 sched_setscheduler(0, SCHED_RR, &fifo_param) == -1)
192 perror("sched_setscheduler");
200 #ifdef CAN_USE_ALARMS
202 /* Now we do want to see it run. But only set
203 * the alarm for twice the interval:
205 itimerval.it_value.tv_usec = interval.tv_nsec / 500;
207 if (setitimer(ITIMER_REAL, &itimerval, 0) == -1) {
213 for (i = 0; !ticked; i++)
220 fprintf(stderr,"Child never ran when it should have.\n");
226 #ifdef STANDALONE_TESTS
227 int main(int argc, char *argv[]) { return fifo(argc, argv); }