From owner-svn-src-head@FreeBSD.ORG Sun Mar 1 13:18:55 2009 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6708B106564A; Sun, 1 Mar 2009 13:18:55 +0000 (UTC) (envelope-from luigi@onelab2.iet.unipi.it) Received: from onelab2.iet.unipi.it (onelab2.iet.unipi.it [131.114.9.129]) by mx1.freebsd.org (Postfix) with ESMTP id 299B58FC0A; Sun, 1 Mar 2009 13:18:55 +0000 (UTC) (envelope-from luigi@onelab2.iet.unipi.it) Received: by onelab2.iet.unipi.it (Postfix, from userid 275) id D795873098; Sun, 1 Mar 2009 14:23:50 +0100 (CET) Date: Sun, 1 Mar 2009 14:23:50 +0100 From: Luigi Rizzo To: Robert Watson Message-ID: <20090301132350.GB54337@onelab2.iet.unipi.it> References: <200903011242.n21CgsV1043573@svn.freebsd.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200903011242.n21CgsV1043573@svn.freebsd.org> User-Agent: Mutt/1.4.2.3i Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r189230 - head/sys/net X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 01 Mar 2009 13:18:55 -0000 On Sun, Mar 01, 2009 at 12:42:54PM +0000, Robert Watson wrote: > Author: rwatson > Date: Sun Mar 1 12:42:54 2009 > New Revision: 189230 > URL: http://svn.freebsd.org/changeset/base/189230 > > Log: > Do a bit of struct ifnet cleanup in preparation for 8.0: group function > pointers together, move padding to the bottom of the structure, and add > two new integer spares due to attrition over time. Remove unused spare > "flags" field, we can use one of the spare ints if we need it later. > > This change requires a rebuild of device driver modules that depend on > the layout of ifnet for binary compatibility reasons. any chance to do similar things for other key kernel structures, such as mbufs and struct bio ? As an example, "struct bio" would benefit from at least one extra intptr_t field to be used for classification purposes (see some recent work we have been doing on disk scheduling). This is a rather trivial and unintrusive change. struct mbuf would benefit from a 'length' field, replacing the hardcoded MLEN/MHLEN. This field would allow us to do several things, e.g.: - use part of the data area to store m_tags instead of having to malloc() them separately; - support multiple (or perhaps even runtime-configurable) mbuf sizes (and corresponding uma zones), so people could experiment with larger MBUFS and perhaps figure out what is the performance impact of using mbuf+clusters instead of individual mbufs for basically every incoming packet. cheers luigi