dispatch_priority.c [plain text]
#include <stdio.h>
#include <dispatch/dispatch.h>
#include <dispatch/queue_private.h>
#include <unistd.h>
#include <stdlib.h>
#include <assert.h>
#include <TargetConditionals.h>
#include "dispatch_test.h"
int done = 0;
#define BLOCKS 128
#define PRIORITIES 3
#if TARGET_OS_EMBEDDED
#define LOOP_COUNT 2000000
#else
#define LOOP_COUNT 100000000
#endif
char *labels[PRIORITIES] = { "LOW", "DEFAULT", "HIGH" };
int priorities[PRIORITIES] = { DISPATCH_QUEUE_PRIORITY_LOW, DISPATCH_QUEUE_PRIORITY_DEFAULT, DISPATCH_QUEUE_PRIORITY_HIGH };
union {
size_t count;
char padding[64];
} counts[PRIORITIES];
#define ITERATIONS (size_t)(PRIORITIES * BLOCKS * 0.50)
size_t iterations = ITERATIONS;
void
histogram(void) {
size_t maxcount = BLOCKS;
size_t sc[PRIORITIES];
size_t total = 0;
size_t x,y;
for (y = 0; y < PRIORITIES; ++y) {
sc[y] = counts[y].count;
}
for (y = 0; y < PRIORITIES; ++y) {
printf("%s: %ld\n", labels[y], sc[y]);
total += sc[y];
double fraction = (double)sc[y] / (double)maxcount;
double value = fraction * (double)80;
for (x = 0; x < 80; ++x) {
printf("%s", (value > x) ? "*" : " ");
}
printf("\n");
}
test_long("blocks completed", total, ITERATIONS);
test_long_less_than("high priority precedence", (long)sc[0], (long)sc[2]);
}
void
cpubusy(void* context)
{
size_t *count = context;
size_t iterdone;
size_t idx;
for (idx = 0; idx < LOOP_COUNT; ++idx) {
if (done) break;
}
if ((iterdone = __sync_sub_and_fetch(&iterations, 1)) == 0) {
__sync_add_and_fetch(&done, 1);
__sync_add_and_fetch(count, 1);
histogram();
test_stop();
exit(0);
} else if (iterdone > 0) {
__sync_add_and_fetch(count, 1);
}
}
void
submit_work(dispatch_queue_t queue, void* context)
{
int i;
for (i = 0; i < BLOCKS; ++i) {
dispatch_async_f(queue, context, cpubusy);
}
#if USE_SET_TARGET_QUEUE
dispatch_release(queue);
#endif
}
int
main(int argc __attribute__((unused)), char* argv[] __attribute__((unused)))
{
dispatch_queue_t q[PRIORITIES];
int i;
#if USE_SET_TARGET_QUEUE
test_start("Dispatch Priority (Set Target Queue)");
for(i = 0; i < PRIORITIES; i++) {
q[i] = dispatch_queue_create(labels[i], NULL);
test_ptr_notnull("q[i]", q[i]);
assert(q[i]);
dispatch_set_target_queue(q[i], dispatch_get_global_queue(priorities[i], 0));
dispatch_queue_set_width(q[i], DISPATCH_QUEUE_WIDTH_MAX_LOGICAL_CPUS);
}
#else
test_start("Dispatch Priority");
for(i = 0; i < PRIORITIES; i++) {
q[i] = dispatch_get_global_queue(priorities[i], 0);
}
#endif
for(i = 0; i < PRIORITIES; i++) {
submit_work(q[i], &counts[i].count);
}
dispatch_main();
return 0;
}