Messages in this thread | | | Subject | Re: very weired random io behavior | From | Ming Zhang <> | Date | Fri, 26 Aug 2005 16:18:48 -0400 |
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sorry. my dumb.
here is not x = (rand() >> 1) << 1; but x = (rand() >> 10) << 10;
file is in bytes while lba is in sector. ;P
ming
On Fri, 2005-08-26 at 16:08 -0400, Ming Zhang wrote:
> --------------------------------------------------- > #define _LARGEFILE64_SOURCE > > #include <stdlib.h> > #include <sys/types.h> > #include <unistd.h> > #include <fcntl.h> > #include <sys/types.h> > #include <sys/stat.h> > > int main(int argc, char *argv[]) > { > int n; > int i, count; > char *name; > char buf[4096]; > int fd; > > if (argc != 3) { > printf("%s name count\n", argv[0]); > exit(1); > } > name = argv[1]; > count = atoi(argv[2]); > > fd = open(name, O_CREAT|O_WRONLY, S_IRWXU); > for (i = 0; i < count; i++) { > unsigned long x; > > x = (rand() >> 1) << 1; > lseek64(fd, x, SEEK_SET); > write(fd, buf, 4096); > } > printf("done\n"); > close(fd); > return 0; > } >
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