From owner-cvs-all Mon Apr 3 13:18: 9 2000 Delivered-To: cvs-all@freebsd.org Received: from mailman.zeta.org.au (mailman.zeta.org.au [203.26.10.16]) by hub.freebsd.org (Postfix) with ESMTP id 96B4337C084; Mon, 3 Apr 2000 13:14:00 -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 (8.8.7/8.8.7) with ESMTP id GAA26068; Tue, 4 Apr 2000 06:13:08 +1000 Date: Tue, 4 Apr 2000 06:12:50 +1000 (EST) From: Bruce Evans X-Sender: bde@alphplex.bde.org To: Poul-Henning Kamp Cc: "Justin T. Gibbs" , cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/kern kern_mib.c vfs_bio.c src/sys/sys buf.h In-Reply-To: <14634.954691700@critter.freebsd.dk> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Sun, 2 Apr 2000, Poul-Henning Kamp wrote: > In message , Bruce Ev > ans writes: > > >"struct bio" is unfortunately even more block-specific than "struct buf", > >since it doesn't have anything like "off_t b_offset". b_offset is > >currently used mainly in the acd driver to handle weird block sizes. > > Well, I have b_offset in my cross-hair, because I know sos will roast > me if I don't handle that case also :-) > > As far as I know, b_offset is only really used for physio and the only > two drivers who understand non DEV_BSIZE multiple requests are the > scsi-tape and atapi-cd drivers. The disk layer already handles special sector sizes without adding much overhead to the usual case. I hope it can do something similar for b_offset. E.g., only one of { b_blkno, b_offset } needs to be valid. Theat one could be maintained by all layers and the other one ignored by all layers. > The question at the heart of this is really: do we want to suffer > the overhead of converting from byte offsets to sector number all > the time or do we want to optimize for the predominantly used > concept of sectors ? I don't want conversions just to match the interface. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message