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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 1.2 2003/06/17 06:29:11 dillon Exp $
41 #include <sys/types.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
); }