writefiles.c

   1 #include <stdio.h>
   2 #include <unistd.h>
   3 #include <stdlib.h>
   4 #include <fcntl.h>
   5 #include <errno.h>
   6 #include <sys/time.h>
   7
   8
   9 static struct timeval tp1,tp2;
  10 static size_t block_size = 64 * 1024;
  11
  12 static void start_timer()
  13 {
  14         gettimeofday(&tp1,NULL);
  15 }
  16
  17 static double end_timer()
  18 {
  19         gettimeofday(&tp2,NULL);
  20         return((tp2.tv_sec - tp1.tv_sec) +
  21                (tp2.tv_usec - tp1.tv_usec)*1.0e-6);
  22 }
  23
  24
  25 static void write_file(char *fname)
  26 {
  27         int fd;
  28         static double total, thisrun;
  29         int n;
  30         char *buf;
  31
  32         buf = malloc(block_size);
  33
  34         if (!buf) {
  35                 printf("Malloc of %d failed\n", block_size);
  36                 exit(1);
  37         }
  38
  39         fd = open(fname, O_WRONLY|O_SYNC);
  40         if (fd == -1) {
  41                 perror(fname);
  42                 free(buf);
  43                 return;
  44         }
  45
  46         while ((n = write(fd, buf, block_size)) > 0) {
  47                 total += n;
  48                 thisrun += n;
  49                 if (end_timer() >= 1.0) {
  50                         printf("%d MB    %g MB/sec\n",
  51                                (int)(total/1.0e6),
  52                                (thisrun*1.0e-6)/end_timer());
  53                         start_timer();
  54                         thisrun = 0;
  55                 }
  56         }
  57
  58         free(buf);
  59         close(fd);
  60 }
  61
  62
  63 static void usage(void)
  64 {
  65         printf("
  66 writefiles - writes to a list of files, showing throughput
  67
  68 Usage: writefiles [options] <files>
  69
  70 Options:
  71     -B size        set the block size in bytes
  72
  73 WARNING: writefiles is a destructive test!
  74
  75 ");
  76 }
  77
  78
  79 int main(int argc, char *argv[])
  80 {
  81         int i;
  82         extern char *optarg;
  83         extern int optind;
  84         int c;
  85
  86         while ((c = getopt(argc, argv, "B:h")) != -1) {
  87                 switch (c) {
  88                 case 'B':
  89                         block_size = strtol(optarg, NULL, 0);
  90                         break;
  91                 case 'h':
  92                 default:
  93                         usage();
  94                         exit(1);
  95                 }
  96         }
  97
  98         argc -= optind;
  99         argv += optind;
 100
 101         if (argc == 0) {
 102                 usage();
 103                 exit(1);
 104         }
 105
 106
 107         start_timer();
 108
 109         while (1) {
 110                 for (i=0; i<argc; i++) {
 111                         write_file(argv[i]);
 112                 }
 113         }
 114
 115         return 0;
 116 }
 117