From owner-freebsd-current Thu Sep 12 4:18:19 2002 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0AD2D37B400 for ; Thu, 12 Sep 2002 04:18:17 -0700 (PDT) Received: from mailman.zeta.org.au (mailman.zeta.org.au [203.26.10.16]) by mx1.FreeBSD.org (Postfix) with ESMTP id 16C1D43E42 for ; Thu, 12 Sep 2002 04:18:16 -0700 (PDT) (envelope-from bde@zeta.org.au) Received: from bde.zeta.org.au (bde.zeta.org.au [203.2.228.102]) by mailman.zeta.org.au (8.9.3/8.8.7) with ESMTP id VAA27369; Thu, 12 Sep 2002 21:18:10 +1000 Date: Thu, 12 Sep 2002 21:22:41 +1000 (EST) From: Bruce Evans X-X-Sender: bde@gamplex.bde.org To: Dan Nelson Cc: current@FreeBSD.ORG Subject: Re: Any problems with increaseing the dump(8) block size? In-Reply-To: <20020912031640.GC13261@dan.emsphone.com> Message-ID: <20020912211300.A6029-100000@gamplex.bde.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG 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