/* * 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); } }