hththt

#
include < stdio.h > #include < time.h > #include < stdlib.h > #include < sys / time.h > #include < sys / resource.h > #include < unistd.h > #include < sys / mman.h >
  int main(int argc, char ** argv) {
    struct timeval tv;
    struct timezone tz;
    int i, j, index, iterations, array_size;
    float * arrayPtr;
    double stop, start, init;
    // Lock down all memory for this process
    if (mlockall(MCL_CURRENT | MCL_FUTURE) < 0) {
      fprintf(stderr, "Memlock error\n");
      exit(1);
    }
    if (argc != 3) {
      fprintf(stderr, "Usage: %s <Size of array><no of iterations>\n", argv[0]);
      exit(1);
    }
    // progname=argv[0];
    array_size = atoi(argv[1]);
    iterations = atoi(argv[2]);
    // Record start
    gettimeofday( & tv, & tz);
    init = tv.tv_sec + tv.tv_usec * 0.000001;
    6
    // create large float arrays
    arrayPtr = calloc(array_size, sizeof(float));
    //initialise array
    for (i = 0; i < array_size; ++i) {
      arrayPtr[i] = 9999.99;
    }
    // Main loop
    // Process full array and time each pass.. Use random number
    // generator to access array randomly .. greater likelihood of paging in unlocked version
    for (j = 0; j < iterations; ++j) {
      gettimeofday( & tv, & tz);
      start = tv.tv_sec + tv.tv_usec * 0.000001;
      // random seed
      srand(time(NULL));
      for (i = 0; i < array_size; ++i) {
        // generate random index
        index = rand() % array_size;
        arrayPtr[index] = arrayPtr[index] / 0.9999;
      }
      gettimeofday( & tv, & tz);
      stop = tv.tv_sec + tv.tv_usec * 0.000001;
      printf("Run time for pass %d is %lf ms\n", j + 1, (stop - start) * 1000);
      // sleep for 10 sec
      sleep(10);
      // Run multiple versions so unlocked versions may be paged during
      // sleep period between passes
    }
    // release memory
    free(arrayPtr);
    munlockall(); // unlock memory
    gettimeofday( & tv, & tz);
    stop = tv.tv_sec + tv.tv_usec * 0.000001;
    printf("Total Run time is %lf ms\n", (stop - init) * 1000);
    return 0;
  }