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Annotation of Net2/tests/benchmarks/randwrite.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Random I/O benchmark.
                      3:  *
                      4:  * Process writes blocks to a
                      5:  * file in a random order. 
                      6:  */
                      7: #include <sys/types.h>
                      8: #include <sys/file.h>
                      9: #include <sys/stat.h>
                     10: 
                     11: char   *malloc();
                     12: 
                     13: main(argc, argv)
                     14:        char *argv[];
                     15: {
                     16:        char *buf;
                     17:        int fd, bn, maxblocks;
                     18:        struct stat sb;
                     19:        register int i, niter;
                     20: 
                     21:        if (argc < 4) {
                     22:                printf("usage: %s file max-file-size #writes\n", argv[0]);
                     23:                exit(1);
                     24:        }
                     25:        fd = open(argv[1], O_WRONLY|O_CREAT|O_TRUNC, 0644);
                     26:        if (fd < 0) {
                     27:                perror(argv[1]);
                     28:                exit(2);
                     29:        }
                     30:        buf = malloc(sb.st_blksize);
                     31:        if (buf == (char *)0) {
                     32:                printf("Couldn't allocate i/o buffer.\n");
                     33:                exit(3);
                     34:        }
                     35:        /* file size is in megabytes */
                     36:        fstat(fd, &sb);
                     37:        maxblocks = atoi(argv[2]) * ((1024 * 1024) / sb.st_blksize);
                     38:        niter = atoi(argv[3]);
                     39:        printf("%d random writes (block size %d)\n", niter, sb.st_blksize);
                     40:        for (i = 0; i < niter; i++) {
                     41:                bn = random() % maxblocks;
                     42:                lseek(fd, bn * sb.st_blksize, L_SET);
                     43:                write(fd, buf, sb.st_blksize);
                     44:        }
                     45: }

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