From owner-cvs-src@FreeBSD.ORG Tue Oct 18 14:41:07 2005 Return-Path: X-Original-To: cvs-src@FreeBSD.org Delivered-To: cvs-src@FreeBSD.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A3AB816A41F; Tue, 18 Oct 2005 14:41:07 +0000 (GMT) (envelope-from obrien@NUXI.com) Received: from dragon.NUXI.org (trang.nuxi.com [66.93.134.19]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4E31E43D4C; Tue, 18 Oct 2005 14:41:07 +0000 (GMT) (envelope-from obrien@NUXI.com) Received: from dragon.NUXI.org (obrien@localhost [127.0.0.1]) by dragon.NUXI.org (8.13.4/8.13.4) with ESMTP id j9IEexZI085144; Tue, 18 Oct 2005 07:40:59 -0700 (PDT) (envelope-from obrien@dragon.NUXI.org) Received: (from obrien@localhost) by dragon.NUXI.org (8.13.4/8.13.1/Submit) id j9IEewwv085143; Tue, 18 Oct 2005 07:40:58 -0700 (PDT) (envelope-from obrien) Date: Tue, 18 Oct 2005 07:40:58 -0700 From: "David O'Brien" To: Andrew Gallatin Message-ID: <20051018144058.GA84920@dragon.NUXI.org> References: <200510172310.j9HNAVPL013057@repoman.freebsd.org> <20051018094402.A29138@grasshopper.cs.duke.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051018094402.A29138@grasshopper.cs.duke.edu> X-Operating-System: FreeBSD 7.0-CURRENT Organization: The NUXI BSD Group X-Pgp-Rsa-Fingerprint: B7 4D 3E E9 11 39 5F A3 90 76 5D 69 58 D9 98 7A X-Pgp-Rsa-Keyid: 1024/34F9F9D5 User-Agent: Mutt/1.5.9i Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, David Xu , cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/amd64/amd64 cpu_switch.S machdep.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: obrien@FreeBSD.org List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 18 Oct 2005 14:41:07 -0000 On Tue, Oct 18, 2005 at 09:44:02AM -0400, Andrew Gallatin wrote: > It is a shame we can't find a way to use the TSC as a timecounter on > SMP systems. It seems that about 40% of the context switch time is > spent just waiting for the PIO read of the ACPI-fast or i8254 to > return. Revision F Opterion's will have the RDTSCP (read serialized TSC pair) instruction that helps some. Slide 13 of http://www.amd.com/us-en/assets/content_type/DownloadableAssets/dwamd_kernel_summit_08_RB.pdf Future Opteron's (or what ever AMD will call it then) will have a P-state invarient TSC in 2007. http://lwn.net/Articles/144098/ -- -- David (obrien@FreeBSD.org)