dispatch_cascade.c [plain text]
#include <stdio.h>
#include <dispatch/dispatch.h>
#include <unistd.h>
#include <stdlib.h>
#include "dispatch_test.h"
int done = 0;
#define QUEUES 80
dispatch_queue_t queues[QUEUES];
#define BLOCKS 10000
union {
size_t index;
char padding[64];
} indices[BLOCKS];
size_t iterations = QUEUES * BLOCKS * 0.25;
void
histogram(void) {
size_t counts[QUEUES] = {};
size_t maxcount = 0;
size_t q;
for (q = 0; q < QUEUES; ++q) {
size_t i;
for (i = 0; i < BLOCKS; ++i) {
if (indices[i].index == q) {
++counts[q];
}
}
}
for (q = 0; q < QUEUES; ++q) {
if (counts[q] > maxcount) {
maxcount = counts[q];
}
}
printf("maxcount = %ld\n", maxcount);
size_t x,y;
for (y = 20; y > 0; --y) {
for (x = 0; x < QUEUES; ++x) {
double fraction = (double)counts[x] / (double)maxcount;
double value = fraction * (double)20;
printf("%s", (value > y) ? "*" : " ");
}
printf("\n");
}
}
void
cascade(void* context) {
size_t idx, *idxptr = context;
if (done) return;
idx = *idxptr + 1;
if (idx < QUEUES) {
*idxptr = idx;
dispatch_async_f(queues[idx], context, cascade);
}
if (__sync_sub_and_fetch(&iterations, 1) == 0) {
done = 1;
histogram();
test_stop();
exit(0);
}
}
int
main(int argc __attribute__((unused)), char* argv[] __attribute__((unused))) {
int i;
test_start("Dispatch Cascade");
for (i = 0; i < QUEUES; ++i) {
queues[i] = dispatch_queue_create(NULL, NULL);
}
for (i = 0; i < BLOCKS; ++i) {
cascade(&indices[i].index);
}
dispatch_main();
return 0;
}