readfiles.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 static int show_latency;
  12 static double min_latency, max_latency, total_time;
  13 static unsigned num_blocks;
  14
  15 static void start_timer()
  16 {
  17         gettimeofday(&tp1,NULL);
  18 }
  19
  20 static double end_timer()
  21 {
  22         gettimeofday(&tp2,NULL);
  23         return((tp2.tv_sec - tp1.tv_sec) +
  24                (tp2.tv_usec - tp1.tv_usec)*1.0e-6);
  25 }
  26
  27
  28 static void read_file(char *fname)
  29 {
  30         int fd;
  31         static double total, thisrun;
  32         int n;
  33         char *buf;
  34         double last_time;
  35
  36         buf = malloc(block_size);
  37
  38         if (!buf) {
  39                 printf("Malloc of %d failed\n", block_size);
  40                 exit(1);
  41         }
  42
  43         fd = open(fname, O_RDONLY);
  44         if (fd == -1) {
  45                 perror(fname);
  46                 free(buf);
  47                 return;
  48         }
  49
  50         if (show_latency) {
  51                 last_time = end_timer();
  52         }
  53
  54         while ((n = read(fd, buf, block_size)) > 0) {
  55                 total += n;
  56                 thisrun += n;
  57                 if (show_latency) {
  58                         double t = end_timer();
  59                         double latency = t - last_time;
  60                         if (latency > max_latency) {
  61                                 max_latency = latency;
  62                         }
  63                         if (min_latency == 0 ||
  64                             latency < min_latency) {
  65                                 min_latency = latency;
  66                         }
  67                         last_time = t;
  68                 }
  69                 if (end_timer() >= 1.0) {
  70                         if (show_latency) {
  71                                 printf("%d MB    %g MB/sec  minlat=%.3f ms  maxlat=%.3f ms\n",
  72                                        (int)(total/1.0e6),
  73                                        (thisrun*1.0e-6)/end_timer(),
  74                                        min_latency * 1000, max_latency * 1000);
  75                         } else {
  76                                 printf("%d MB    %g MB/sec\n",
  77                                        (int)(total/1.0e6),
  78                                        (thisrun*1.0e-6)/end_timer());
  79                         }
  80
  81                         start_timer();
  82                         last_time = 0;
  83                         thisrun = 0;
  84                         min_latency = max_latency = 0;
  85                 }
  86         }
  87
  88         free(buf);
  89         close(fd);
  90 }
  91
  92
  93 static void usage(void)
  94 {
  95         printf("\n" \
  96 "readfiles - reads from a list of files, showing read throughput\n" \
  97 "\n" \
  98 "Usage: readfiles [options] <files>\n" \
  99 "\n" \
 100 "Options:\n" \
 101 "    -B size        set the block size in bytes\n" \
 102 "    -L             show latencies\n" \
 103 "");
 104 }
 105
 106 int main(int argc, char *argv[])
 107 {
 108         int i;
 109         extern char *optarg;
 110         extern int optind;
 111         int c;
 112
 113         while ((c = getopt(argc, argv, "B:hL")) != -1) {
 114                 switch (c) {
 115                 case 'B':
 116                         block_size = strtol(optarg, NULL, 0);
 117                         break;
 118                 case 'L':
 119                         show_latency = 1;
 120                         break;
 121                 case 'h':
 122                 default:
 123                         usage();
 124                         exit(1);
 125                 }
 126         }
 127
 128         argc -= optind;
 129         argv += optind;
 130
 131         if (argc == 0) {
 132                 usage();
 133                 exit(1);
 134         }
 135
 136         start_timer();
 137
 138         while (1) {
 139                 for (i=0; i < argc; i++) {
 140                         read_file(argv[i]);
 141                 }
 142         }
 143
 144         return 0;
 145 }
 146