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#include <stdio.h>
#include <pthread.h>
#include <sched.h>
#include <string.h>
#include <err.h>
#include "bench.h"
static char name[] = "Self Overhead";
static char doc[] =
"\tThe time needed for the highest priority thread to perform the\n"
"\tpthread_self() operation, for the following numbers of threads:\n"
"\t1, 21, 101, 1023";
static int nthreads = 1;
pthread_t children[1024];
void *
child() {
pause();
}
void
numthreads(n)
int n;
{
int error;
pthread_attr_t small_stack_attr;
pthread_attr_init(&small_stack_attr);
pthread_attr_setstacksize(&small_stack_attr, PTHREAD_STACK_MIN);
while (nthreads < n) {
error = pthread_create(&children[nthreads],
&small_stack_attr, child, NULL);
if (error != 0)
errx(1, "pthread_create #%d: %s", nthreads,
strerror(error));
sched_yield();
nthreads++;
}
while (nthreads > n) {
error = pthread_cancel(children[nthreads - 1]);
if (error != 0)
errx(1, "pthread_cancel: %s", strerror(error));
sched_yield();
nthreads --;
}
printf("\n#threads: %d\n", nthreads);
}
void
doit(b, n)
bench_t *b;
int n;
{
numthreads(n);
bench_amortize(b, BENCH_LOOPS) {
pthread_self();
}
bench_report(b);
}
int
main() {
bench_t b;
bench_init(&b, name, doc, "per call");
bench_header(&b);
doit(&b, 1);
doit(&b, 21);
doit(&b, 101);
doit(&b, 1023);
exit(0);
}
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