Attachment 156213 Details for Bug 198149 – threadspin.c

[patch] threadspin.c

threadspin.c (text/plain), 2.20 KB, created by John Baldwin on 2015-05-01 15:35:31 UTC

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Creator: John Baldwin

Created: 2015-05-01 15:35:31 UTC

Size: 2.20 KB

patch

obsolete

>#include <sys/param.h>
>#include <assert.h>
>#include <err.h>
>#include <math.h>
>#include <pthread.h>
>#include <pthread_np.h>
>#include <stdbool.h>
>#include <stdio.h>
>#include <stdlib.h>
>#include <strings.h>
>#include <unistd.h>
>
>static volatile int dying;
>static bool bind_cpus;
>
>static void
>usage(void)
>{
>
>	fprintf(stderr, "Usage: threadspin [-b]\n");
>	exit(1);
>}
>
>/* Bind the current thread to the specified CPU. */
>static void
>bind_cpu(int cpu)
>{
>	cpuset_t set;
>
>	CPU_ZERO(&set);
>	CPU_SET(cpu, &set);
>	if (pthread_setaffinity_np(pthread_self(), sizeof(set), &set) < 0)
>		err(1, "pthread_setaffinity_np(%d)", cpu);
>}
>
>static void *
>worker(void *arg)
>{
>	double x;
>	int cpu;
>
>	cpu = (intptr_t)arg;
>	if (bind_cpus)
>		bind_cpu(cpu);
>	x = (double)random();
>	while (!dying) {
>		x = sqrt(x);
>		x *= x;
>	}
>	pthread_exit(NULL);
>}
>
>int
>main(int ac, char **av)
>{
>	cpuset_t all_cpus;
>	pthread_t *threads;
>	int ch, cpu, error, i, ncpu;
>
>	bind_cpus = false;
>	while ((ch = getopt(ac, av, "b")) != -1)
>		switch (ch) {
>		case 'b':
>			bind_cpus = true;
>			break;
>		default:
>			usage();
>			break;
>		}
>
>	/*
>	 * Find all the CPUs this program is eligible to run on and use
>	 * this as our global set.  This means you can use cpuset to
>	 * restrict this program to only run on a subset of CPUs.
>	 */
>	if (cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID, -1,
>	    sizeof(all_cpus), &all_cpus) < 0)
>		err(1, "cpuset_getaffinity");
>#ifdef CPU_COUNT
>	ncpu = CPU_COUNT(&all_cpus);
>#else
>	for (ncpu = 0, i = 0; i < CPU_SETSIZE; i++) {
>		if (CPU_ISSET(i, &all_cpus))
>			ncpu++;
>	}
>#endif
>
>	printf("main: PID %d\n", getpid());
>	printf("main: creating threads\n");
>	threads = calloc(ncpu, sizeof(*threads));
>	if (threads == NULL)
>		err(1, "calloc");
>	for (i = 0; i < ncpu; i++) {
>		assert(!CPU_EMPTY(&all_cpus));
>		cpu = CPU_FFS(&all_cpus) - 1;
>		CPU_CLR(cpu, &all_cpus);
>		error = pthread_create(&threads[i], NULL, worker,
>		    (void *)(uintptr_t)cpu);
>		if (error)
>			errc(1, error, "pthread_create");
>	}
>	assert(CPU_EMPTY(&all_cpus));
>
>	(void)getchar();
>	printf("main: killing threads\n");
>	dying = 1;
>	printf("main: joining threads\n");
>	for (i = 0; i < ncpu; i++) {
>		error = pthread_join(threads[i], NULL);
>		if (error)
>			errc(1, error, "pthread_join");
>	}
>
>	return (0);
>}

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Attachments on bug 198149: 156213 | 156477 | 156483