From owner-freebsd-current@FreeBSD.ORG Mon Dec 6 19:11:02 2010 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from [127.0.0.1] (freefall.freebsd.org [IPv6:2001:4f8:fff6::28]) by hub.freebsd.org (Postfix) with ESMTP id B827E1065673; Mon, 6 Dec 2010 19:11:02 +0000 (UTC) (envelope-from jkim@FreeBSD.org) From: Jung-uk Kim To: Andriy Gapon Date: Mon, 6 Dec 2010 14:10:34 -0500 User-Agent: KMail/1.6.2 References: <4CF92852.20705@freebsd.org> <201012061334.22475.jkim@FreeBSD.org> <4CFD31E0.8070107@freebsd.org> In-Reply-To: <4CFD31E0.8070107@freebsd.org> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201012061410.46351.jkim@FreeBSD.org> Cc: freebsd-current@freebsd.org Subject: Re: non-invariant tsc and cputicker 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: Mon, 06 Dec 2010 19:11:02 -0000 On Monday 06 December 2010 01:56 pm, Andriy Gapon wrote: > on 06/12/2010 20:34 Jung-uk Kim said the following: > > I understand that. However, it is not clear to me why you want > > to pessimize performance of old hardware. If you can convince me > > old hardware with slow timecounter hardware (e.g., i8254) does > > not hurt too much, maybe it's okay. > > Overlooked this point - TSC can be very well used as a timecounter. > And in that case non-invariant TSC would veto P-state changes, > which is the proper thing to do, IMO. Yes, thanks to njl. He made it "somewhat bogus" from "totally bogus". I made it "almost correct" from "somewhat bogus" for modern P-state invariant CPUs. ;-) Jung-uk Kim