From owner-freebsd-hackers@FreeBSD.ORG Tue Mar 29 11:11:10 2005 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id BBA5216A4CE for ; Tue, 29 Mar 2005 11:11:10 +0000 (GMT) Received: from mail20.syd.optusnet.com.au (mail20.syd.optusnet.com.au [211.29.132.201]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1983B43D3F for ; Tue, 29 Mar 2005 11:11:10 +0000 (GMT) (envelope-from PeterJeremy@optushome.com.au) Received: from cirb503493.alcatel.com.au (c211-30-75-229.belrs2.nsw.optusnet.com.au [211.30.75.229]) j2TBB8Oj023208 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NO); Tue, 29 Mar 2005 21:11:08 +1000 Received: from cirb503493.alcatel.com.au (localhost.alcatel.com.au [127.0.0.1])j2TBB77l070109; Tue, 29 Mar 2005 21:11:07 +1000 (EST) (envelope-from pjeremy@cirb503493.alcatel.com.au) Received: (from pjeremy@localhost)j2TBB7MK070108; Tue, 29 Mar 2005 21:11:07 +1000 (EST) (envelope-from pjeremy) Date: Tue, 29 Mar 2005 21:11:07 +1000 From: Peter Jeremy To: David Leimbach Message-ID: <20050329111107.GD69824@cirb503493.alcatel.com.au> References: <423C15C5.6040902@fsn.hu> <20050327133059.3d68a78c@Magellan.Leidinger.net> <20050327134044.GM78512@silverwraith.com> <20050327162839.2fafa6aa@Magellan.Leidinger.net> <5bbfe7d405032823144fc1af7b@mail.gmail.com> <5bbfe7d405032823232103d537@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5bbfe7d405032823232103d537@mail.gmail.com> User-Agent: Mutt/1.4.2i cc: hackers@freebsd.org Subject: Re: Fwd: 5-STABLE kernel build with icc broken X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 29 Mar 2005 11:11:10 -0000 On Mon, 2005-Mar-28 23:23:19 -0800, David Leimbach wrote: >meant to send this to the list too... sorry >> Are you implying DragonFly uses FPU/SIMD? For that matter does any kernel? > >I believe it does use SIMD for some of it's fast memcopy stuff for >it's messaging system >actually. I remember Matt saying he was working on it. > >http://leaf.dragonflybsd.org/mailarchive/kernel/2004-04/msg00262.html That's almost a year ago and specifically for the amd64. Does anyone know what the results were? >If you can manage the alignment issues it can be a huge win. For message passing within the kernel, you should be able to mandate alignment as part of the API. I see the bigger issue being the need to save/restore the SIMD engine's state during a system call. Currently, this is only saved on if a different process wants to use the SIMD engine. For MMX, the SIMD state is the FPU state - which is non-trivial. The little reading I've done suggests that SSE and SSE2 are even larger. Saving the SIMD state would be more expensive that using integer registers for small (and probably medium-sized) copies. -- Peter Jeremy