From owner-freebsd-arch@FreeBSD.ORG Tue Sep 9 23:20:47 2003 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DFE9816A4BF for ; Tue, 9 Sep 2003 23:20:47 -0700 (PDT) Received: from critter.freebsd.dk (p26.n-sfpop02.stsn.com [199.107.153.26]) by mx1.FreeBSD.org (Postfix) with ESMTP id 73B6743FD7 for ; Tue, 9 Sep 2003 23:20:47 -0700 (PDT) (envelope-from phk@phk.freebsd.dk) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.12.9/8.12.9) with ESMTP id h8A6KlIP005149 for ; Wed, 10 Sep 2003 08:20:47 +0200 (CEST) (envelope-from phk@phk.freebsd.dk) To: arch@freebsd.org From: Poul-Henning Kamp Date: Wed, 10 Sep 2003 08:20:47 +0200 Message-ID: <5148.1063174847@critter.freebsd.dk> Subject: The struct buf junta met... X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 Sep 2003 06:20:48 -0000 The struct buf junta met at an undisclosed location, and this is what we found out: With the 5-stable branch (still) being 3-4 in the future, we want to get as much as the API changes into the stable branch as possible, in order to not do another "3.x mistake". The things you can expect to see appearing (provided we can make it work) is: 1. Move floppies & CD's under GEOM. 2. Move the vcount() to the dev_t for VCHR. This removes one icky problem from vnode locking. 3. Vnode bypass for userland device access. This is the stuff I posted a prototype of some time ago: Go directly from the filedesc switch to SPECFS thus bypassing vnodes and vnode locking intirely and going Giant-free for drivers that support this. 4. Scatter/Gather mapped/unmapped struct bio. This allows an I/O request to be composed of a number of pages spread out in physical memory. 5. Shoot pbufs In swap_pager.c, vfs_cluster, spec_getpages, AIO, O_DIRECT... We have a lot of ideas going forward from that point, but they are not concrete enough to actually formulate as a plan yet. We will try to explain this coherently at the devsummit this weekend and in email subsequent to that. Secretary for the Buf Junta Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.