testing/dispatch_cascade.c

   1 #include <stdio.h>
   2 #include <dispatch/dispatch.h>
   3 #include <unistd.h>
   4 #include <stdlib.h>
   5
   6 #include "dispatch_test.h"
   7
   8 int done = 0;
   9
  10 #define QUEUES 80
  11 dispatch_queue_t queues[QUEUES];
  12
  13
  14 #define BLOCKS 10000
  15 union {
  16         size_t index;
  17         char padding[64];
  18 } indices[BLOCKS];
  19
  20 size_t iterations = QUEUES * BLOCKS * 0.25;
  21
  22 void
  23 histogram(void) {
  24         size_t counts[QUEUES] = {};
  25         size_t maxcount = 0;
  26
  27         size_t q;
  28         for (q = 0; q < QUEUES; ++q) {
  29                 size_t i;
  30                 for (i = 0; i < BLOCKS; ++i) {
  31                         if (indices[i].index == q) {
  32                                 ++counts[q];
  33                         }
  34                 }
  35         }
  36
  37         for (q = 0; q < QUEUES; ++q) {
  38                 if (counts[q] > maxcount) {
  39                         maxcount = counts[q];
  40                 }
  41         }
  42
  43         printf("maxcount = %ld\n", maxcount);
  44
  45         size_t x,y;
  46         for (y = 20; y > 0; --y) {
  47                 for (x = 0; x < QUEUES; ++x) {
  48                         double fraction = (double)counts[x] / (double)maxcount;
  49                         double value = fraction * (double)20;
  50                         printf("%s", (value > y) ? "*" : " ");
  51                 }
  52                 printf("\n");
  53         }
  54 }
  55
  56 void
  57 cascade(void* context) {
  58         size_t idx, *idxptr = context;
  59
  60         if (done) return;
  61
  62         idx = *idxptr + 1;
  63
  64         if (idx < QUEUES) {
  65                 *idxptr = idx;
  66                 dispatch_async_f(queues[idx], context, cascade);
  67         }
  68
  69         if (__sync_sub_and_fetch(&iterations, 1) == 0) {
  70                 done = 1;
  71                 histogram();
  72                 test_stop();
  73                 exit(0);
  74         }
  75 }
  76
  77 int
  78 main(int argc __attribute__((unused)), char* argv[] __attribute__((unused))) {
  79         int i;
  80
  81         test_start("Dispatch Cascade");
  82
  83         for (i = 0; i < QUEUES; ++i) {
  84                 queues[i] = dispatch_queue_create(NULL, NULL);
  85         }
  86
  87         for (i = 0; i < BLOCKS; ++i) {
  88                 cascade(&indices[i].index);
  89         }
  90
  91         dispatch_main();
  92
  93         return 0;
  94 }