Date: Thu, 12 Sep 2002 21:22:41 +1000 (EST) From: Bruce Evans <bde@zeta.org.au> To: Dan Nelson <dnelson@allantgroup.com> Cc: current@FreeBSD.ORG Subject: Re: Any problems with increaseing the dump(8) block size? Message-ID: <20020912211300.A6029-100000@gamplex.bde.org> In-Reply-To: <20020912031640.GC13261@dan.emsphone.com>
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On Wed, 11 Sep 2002, Dan Nelson wrote: > In the last episode (Sep 11), David O'Brien said: > > I'd like to make this commit to get better performance on today's > > streaming tape drives. It seems my DLT drive doesn't stream well > > with the default block size of '10'. > > Only if we also raise dd's and tar's default blocksizes to 64k as well :) > > How about raising BUFSIZE (no smiley)? Tru64 and Linux both have an 8k > stdio buffer. Why do the other systems use such a small buffer? :-) BSD stdio normally uses st_blksize, which is 16K for regular files on ffs filesystems created with the current defaults, and 8K for regular files on ffs filesystems ceeated with old defaults. st_blksize used to be quite variable and usually too large (64K) for special files, but it is now not very variable and usually too small (PAGE_SIZE) for special files. BUFSIZ is only used in broken cases where the kernel sets st_blksize to 0 or a naive application uses BUFSIZ or the old setbuf() interface. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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