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Diffstat (limited to 'tools/regression/p1003_1b/yield.c')
| -rw-r--r-- | tools/regression/p1003_1b/yield.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/tools/regression/p1003_1b/yield.c b/tools/regression/p1003_1b/yield.c new file mode 100644 index 0000000..ac31a99 --- /dev/null +++ b/tools/regression/p1003_1b/yield.c @@ -0,0 +1,197 @@ +/* + * Copyright (c) 1996-1999 + * HD Associates, Inc. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by HD Associates, Inc + * 4. Neither the name of the author nor the names of any co-contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY HD ASSOCIATES AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL HD ASSOCIATES OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * $FreeBSD$ + * + */ +#include <sys/types.h> +#include <unistd.h> +#include <stdlib.h> +#include <stdio.h> +#include <errno.h> +#include <err.h> +#include <fcntl.h> +#include <sys/types.h> +#include <sys/mman.h> +#include <sched.h> +#include <stdlib.h> +#include <sys/wait.h> + +#include "prutil.h" + +/* buzz: busy wait a random amount of time. + */ +static void buzz(int n) +{ + volatile int i; + int m = random() & 0x0ffff; + for (i = 0; i < m; i++) + ; +} + +/* Yield: Verify that "sched_yield" works for the FIFO case. + * This runs several processes and verifies that the yield seems + * to permit the next one on the ready queue to run. + */ +int yield(int argc, char *argv[]) +{ + volatile int *p; + int i; + int nslaves, n; + int master, slave; + pid_t youngest = !0; /* Our youngest child */ + struct sched_param set, got; + int nloops = 1000; + + errno = 0; + + set.sched_priority = sched_get_priority_max(SCHED_FIFO); + if (set.sched_priority == -1 && errno) { + perror("sched_get_priority_max"); + exit(errno); + } + + if (argc == 1) + n = nslaves = 10; + + else if (argc != 2) { + fprintf(stderr, "usage: prog [n_instances]\n"); + exit(-1); + } + else + n = nslaves = atoi(argv[1]); + + p = (int *)mmap(0, sizeof(int), + PROT_READ|PROT_WRITE, MAP_ANON|MAP_SHARED|MAP_INHERIT, -1, 0); + + if (p == (int *)-1) + err(errno, "mmap"); + + *p = 0; + + if (sched_setscheduler(0, SCHED_FIFO, &set) == -1) + err(errno, "sched_setscheduler"); + + /* I better still be SCHED_FIFO and RT_PRIO_MAX: + */ + (void)sched_is(__LINE__, &got, SCHED_FIFO); + if (got.sched_priority != set.sched_priority) { + fprintf(stderr, "line %d: scheduler screwup\n", + __LINE__); + exit(-1); + } + + slave = 0; + master = 1; + + /* Fork off the slaves. + */ + for (i = 0; i < nslaves; i++) { + if ((youngest = fork()) == 0) { + /* I better still be SCHED_FIFO and RT_PRIO_MAX: + */ + (void)sched_is(__LINE__, &got, SCHED_FIFO); + + if (got.sched_priority != set.sched_priority) { + fprintf(stderr, "line %d: scheduler screwup\n", + __LINE__); + exit(-1); + } + + master = 0; /* I'm a slave */ + slave = i + 1; /* With this flag */ + *p = slave; /* And I live */ + break; + } + } + + if (master) { + /* If we conform the slave processes haven't run yet. + * The master must yield to let the first slave run. + */ + if (*p != 0) { + fprintf(stderr, + "Error at line %d: Writer %d has run\n", __LINE__, *p); + exit(-1); + } + } + + /* Now the master yields, the first slave runs, and yields, + * next runs, yields, ... + * + * So the master should get through this first. + */ + + if (sched_yield() == -1) + err(errno, "sched_yield"); + + if (master) { + int status; + + /* The final slave process should be the last one started. + */ + if (*p != nslaves) { + fprintf(stderr, + "Error at line %d: Final slave is %d not %d.\n", + __LINE__, *p, nslaves); + exit(-1); + } + + /* Wait for our youngest to exit: + */ + waitpid(youngest, &status, 0); + + exit(WEXITSTATUS(status)); /* Let the slaves continue */ + } + + /* Now the first one has started up. + */ + for (i = 0; i < nloops; i++) { + if (((*p) % nslaves) != + ((slave + nslaves - 1) % nslaves)) { + fprintf(stderr, "%d ran before %d on iteration %d.\n", + *p, slave, i); + exit(-1); + } + *p = slave; + + /* Delay some random amount of time. + */ + buzz(slave); + + if (sched_yield() == -1) + err(errno, "sched_yield"); + } + + exit(0); +} +#ifdef STANDALONE_TESTS +int main(int argc, char *argv[]) { return yield(argc, argv); } +#endif |
