BSD 4_4 development

[unix-history] / usr / src / sys / tests / benchmarks / randwrite.c

/*
* Random I/O benchmark.
*
* Process writes blocks to 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 < 4) {
               printf("usage: %s file max-file-size #writes\n", argv[0]);
               exit(1);
       }
       fd = open(argv[1], O_WRONLY|O_CREAT|O_TRUNC, 0644);
       if (fd < 0) {
               perror(argv[1]);
               exit(2);
       }
       buf = malloc(sb.st_blksize);
       if (buf == (char *)0) {
               printf("Couldn't allocate i/o buffer.\n");
               exit(3);
       }
       /* file size is in megabytes */
       fstat(fd, &sb);
       maxblocks = atoi(argv[2]) * ((1024 * 1024) / sb.st_blksize);
       niter = atoi(argv[3]);
       printf("%d random writes (block size %d)\n", niter, sb.st_blksize);
       for (i = 0; i < niter; i++) {
               bn = random() % maxblocks;
               lseek(fd, bn * sb.st_blksize, L_SET);
               write(fd, buf, sb.st_blksize);
       }
}