From owner-freebsd-current@FreeBSD.ORG Wed Mar 31 12:34:47 2004 Return-Path: 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 14C8816A4CE; Wed, 31 Mar 2004 12:34:47 -0800 (PST) Received: from fledge.watson.org (fledge.watson.org [204.156.12.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id B30E243D3F; Wed, 31 Mar 2004 12:34:46 -0800 (PST) (envelope-from robert@fledge.watson.org) Received: from fledge.watson.org (localhost [127.0.0.1]) by fledge.watson.org (8.12.10/8.12.10) with ESMTP id i2VKWGxC017304; Wed, 31 Mar 2004 15:32:16 -0500 (EST) (envelope-from robert@fledge.watson.org) Received: from localhost (robert@localhost)i2VKWGxt017301; Wed, 31 Mar 2004 15:32:16 -0500 (EST) (envelope-from robert@fledge.watson.org) Date: Wed, 31 Mar 2004 15:32:15 -0500 (EST) From: Robert Watson X-Sender: robert@fledge.watson.org To: Andre Oppermann In-Reply-To: <406B0CB8.6030409@freebsd.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: current@freebsd.org Subject: Re: Interesting cross-fertilization with DfBSD X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 31 Mar 2004 20:34:47 -0000 On Wed, 31 Mar 2004, Andre Oppermann wrote: > * Avoiding the KVM mappings and the related kernel_object > manipulations > required for those mappings saves a lot of cpu cycles when all > > you > want is a quick mapping into KVM. Yeah -- these issue was discussed extensively at the USENIX ATC FreeBSD Developer Summit last summer in San Antonio, and also to some extent at the FreeBSD Developer Summit following BSDCon in San Francisco last fall. There are tentative plans to move to unmapped and deferred mapping buffers in our I/O system (Peter, Jeff, Kirk, and Poul-Henning have the details), but this work is scheduled to be one of the major goals for the 6.x branch. Part of our goal, though, in preparing for 5.x has been to try and make sure APIs are moving in directions to support that goal. A simultaneous goal is to untangle the web of connections between the VM system meta-data and remaining mocked up (duplicated) meta-data for the buffer cache. It will be very interesting to see how it works out for Matt, and where his proposed approach is similar to or different from the tentative plans we've discussed. Obviously, we're willing to learn from any positive discoveries (and less positive ones) he makes along the way :-). Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Senior Research Scientist, McAfee Research