BSD 4_4 development

[unix-history] / usr / src / sys / tests / benchmarks / bench-4.1 / randbread.c

/*
* Random I/O benchmark.
*
* Process reads blocks from a
* file in a random order. 
*/
#include <sys/types.h>
#include <sys/file.h>
#include <sys/stat.h>

char    *malloc();

main(argc, argv)
       char *argv[];
{
       char *buf;
       int fd, bn, maxblocks;
       struct stat sb;
       register int i, niter;

       if (argc < 3) {
               printf("usage: %s file #reads\n", argv[0]);
               exit(1);
       }
       fd = open(argv[1], 0);
       if (fd < 0) {
               perror(argv[1]);
               exit(2);
       }
       buf = malloc(1024);
       if (buf == (char *)0) {
               printf("Couldn't allocate i/o buffer.\n");
               exit(3);
       }
       fstat(fd, &sb);
       niter = atoi(argv[2]);
       printf("%d random block reads, file size %d kb (bsize %d)\n",
           niter, sb.st_size / 1024, 1024);
       for (i = 0; i < niter; i++) {
               bn = (random() % sb.st_size) / sb.st_size;
               lseek(fd, bn * 1024, 0);
               read(fd, buf, 1024);
       }
}