From owner-freebsd-current@FreeBSD.ORG Sat Apr 19 12:14:11 2008 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id CA853106567C for ; Sat, 19 Apr 2008 12:14:11 +0000 (UTC) (envelope-from doconnor@gsoft.com.au) Received: from cain.gsoft.com.au (cain.gsoft.com.au [203.31.81.10]) by mx1.freebsd.org (Postfix) with ESMTP id D51018FC1B for ; Sat, 19 Apr 2008 12:14:10 +0000 (UTC) (envelope-from doconnor@gsoft.com.au) Received: from inchoate.gsoft.com.au (ppp121-45-67-45.lns10.adl6.internode.on.net [121.45.67.45]) (authenticated bits=0) by cain.gsoft.com.au (8.13.8/8.13.8) with ESMTP id m3JCAiqU094670 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sat, 19 Apr 2008 21:41:13 +0930 (CST) (envelope-from doconnor@gsoft.com.au) From: "Daniel O'Connor" To: freebsd-current@freebsd.org Date: Fri, 18 Apr 2008 12:35:23 +0930 User-Agent: KMail/1.9.7 References: <20080418003203.GB11705@dragon.NUXI.org> <48080276.3040203@elischer.org> In-Reply-To: <48080276.3040203@elischer.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200804181235.29530.doconnor@gsoft.com.au> X-Spam-Score: -0.714 () BAYES_00,DATE_IN_PAST_24_48,RDNS_DYNAMIC X-Scanned-By: MIMEDefang 2.63 on 203.31.81.10 Cc: gnn@freebsd.org, Julian Elischer , Andrew Gallatin Subject: Re: TSC Timecounter and multi-core/SMP X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 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: Sat, 19 Apr 2008 12:14:11 -0000 On Fri, 18 Apr 2008, Julian Elischer wrote: > David O'Brien wrote: > > The TSC on K8 is not invariant - its rate of change is affected by > > P-state changes. > > > > The TSC on Greyhound (Family 10h) is invariant. > > [but as stated above, is not synced with other cores] > > You'd think that an invariant sync'd clock (fast to read) of some > type would have been done by someone by now.. The software people > have been asking for this for the last decade at least. Probably because it's very very difficult to get right :) -- Daniel O'Connor software and network engineer for Genesis Software - http://www.gsoft.com.au "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C