From owner-freebsd-hackers Sun Feb 22 10:07:23 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id KAA18681 for freebsd-hackers-outgoing; Sun, 22 Feb 1998 10:07:23 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from narnia.plutotech.com (narnia.plutotech.com [206.168.67.130]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id KAA18675 for ; Sun, 22 Feb 1998 10:07:20 -0800 (PST) (envelope-from gibbs@narnia.plutotech.com) Received: (from gibbs@localhost) by narnia.plutotech.com (8.8.8/8.7.3) id LAA06017; Sun, 22 Feb 1998 11:04:14 -0700 (MST) Date: Sun, 22 Feb 1998 11:04:14 -0700 (MST) From: "Justin T. Gibbs" Message-Id: <199802221804.LAA06017@narnia.plutotech.com> To: Greg Lehey cc: hackers@FreeBSD.ORG Subject: Re: New SoftUpdates test kit Newsgroups: pluto.freebsd.hackers In-Reply-To: <19980222175710.04357@freebie.lemis.com> <199802220738.XAA06227@dingo.cdrom.com> <19980222183233.41134@freebie.lemis.com> User-Agent: tin/pre-1.4-971204 (UNIX) (FreeBSD/3.0-CURRENT (i386)) Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > Mike, back to the discussion of policy. vinum needs some way to > associate the buffer returned to the b_iodone function with its > internal requests. CCD does this by including the buffer header in > the internal request. The obvious alternative is to use one of > b_driver[12] to point to the other information. The trouble is that > scsi_strategy seems to use both of them. Consider a few > possibilities: It has been discussed before that b_driver* should go away. The CAM SCSI layer does not use these fields which means that the last reference in our code is going away. Please don't add another instance. Struct bufs are pervasive and keeping their size small enough to be efficiently allocated is important. I'd have to go look to see how close we are to a power of two in size right now, but even if removing these fields doesn't shrink us down a malloc bucket size, it will give us room to add things like pointers for buffer chaining for larger than 64k I/O requests. -- Justin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message