openmp/runtime/test/affinity/redetect.c

   1 // RUN: %libomp-compile
   2 // RUN: env KMP_AFFINITY=none %libomp-run
   3 // REQUIRES: linux
   4
   5 // Check if forked child process resets affinity properly by restricting
   6 // child's affinity to a subset of the parent and then checking it after
   7 // a parallel region
   8
   9 #define _GNU_SOURCE
  10 #include "libomp_test_affinity.h"
  11 #include <omp.h>
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <sys/wait.h>
  15 #include <sys/types.h>
  16 #include <unistd.h>
  17
  18 // Set the affinity mask of the calling thread to a proper subset of the
  19 // original affinity mask, specifically, one processor less.
  20 void set_subset_affinity(affinity_mask_t *mask) {
  21   int cpu;
  22   affinity_mask_t *original_mask = affinity_mask_alloc();
  23   affinity_mask_copy(original_mask, mask);
  24   // Find first processor to clear for subset mask
  25   for (cpu = 0; cpu <= AFFINITY_MAX_CPUS; ++cpu) {
  26     if (affinity_mask_isset(original_mask, cpu)) {
  27       affinity_mask_clr(mask, cpu);
  28       break;
  29     }
  30   }
  31   affinity_mask_free(original_mask);
  32   set_thread_affinity(mask);
  33 }
  34
  35 int main(int argc, char **argv) {
  36   char buf[1024] = {0};
  37   char *other_buf;
  38   size_t n;
  39   int child_exit_status, exit_status;
  40   affinity_mask_t *mask = affinity_mask_alloc();
  41   get_thread_affinity(mask);
  42   n = affinity_mask_snprintf(buf, sizeof(buf), mask);
  43   printf("Orignal Mask: %s\n", buf);
  44
  45   if (affinity_mask_count(mask) == 1) {
  46     printf("Only one processor in affinity mask, skipping test.\n");
  47     exit(EXIT_SUCCESS);
  48   }
  49
  50   #pragma omp parallel
  51   {
  52     #pragma omp single
  53     printf("Hello! Thread %d executed single region in parent process\n",
  54            omp_get_thread_num());
  55   }
  56
  57   pid_t pid = fork();
  58   if (pid < 0) {
  59     perror("fork()");
  60     exit(EXIT_FAILURE);
  61   }
  62
  63   if (pid == 0) {
  64     // Let child set a new initial mask
  65     set_subset_affinity(mask);
  66     #pragma omp parallel
  67     {
  68       #pragma omp single
  69       printf("Hello! Thread %d executed single region in child process\n",
  70              omp_get_thread_num());
  71     }
  72     affinity_mask_t *new_mask = affinity_mask_alloc();
  73     get_thread_affinity(new_mask);
  74     if (!affinity_mask_equal(mask, new_mask)) {
  75       affinity_mask_snprintf(buf, sizeof(buf), mask);
  76       fprintf(stderr, "Original Mask = %s\n", buf);
  77       affinity_mask_snprintf(buf, sizeof(buf), new_mask);
  78       fprintf(stderr, "New Mask = %s\n", buf);
  79       affinity_mask_free(new_mask);
  80       fprintf(stderr, "Child affinity mask did not reset properly\n");
  81       exit(EXIT_FAILURE);
  82     }
  83     affinity_mask_free(new_mask);
  84     exit_status = EXIT_SUCCESS;
  85   } else {
  86     pid_t child_pid = pid;
  87     pid = wait(&child_exit_status);
  88     if (pid == -1) {
  89       perror("wait()");
  90       exit(EXIT_FAILURE);
  91     }
  92     if (WIFEXITED(child_exit_status)) {
  93       exit_status = WEXITSTATUS(child_exit_status);
  94     } else {
  95       exit_status = EXIT_FAILURE;
  96     }
  97   }
  98
  99   affinity_mask_free(mask);
 100   return exit_status;
 101 }