Date: Sun, 02 Apr 2000 18:08:20 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Bruce Evans <bde@zeta.org.au> Cc: "Justin T. Gibbs" <gibbs@FreeBSD.org>, 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 Message-ID: <14634.954691700@critter.freebsd.dk> In-Reply-To: Your message of "Mon, 03 Apr 2000 01:54:07 %2B1000." <Pine.BSF.4.21.0004030144330.1715-100000@alphplex.bde.org>
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In message <Pine.BSF.4.21.0004030144330.1715-100000@alphplex.bde.org>, 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. This ties in somewhat with Justins email where he restates the idea Bruce half-jokingly proposed about a year ago: use struct uio for io carrier. 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 ? -- Poul-Henning Kamp FreeBSD coreteam member phk@FreeBSD.ORG "Real hackers run -current on their laptop." FreeBSD -- It will take a long time before progress goes too far! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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