From owner-freebsd-current Fri Aug 23 14:25:37 2002 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 3D79937B400 for ; Fri, 23 Aug 2002 14:25:35 -0700 (PDT) Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.86.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id 6EE3D43E3B for ; Fri, 23 Aug 2002 14:25:34 -0700 (PDT) (envelope-from phk@critter.freebsd.dk) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.12.3/8.12.2) with ESMTP id g7NLMAoc030324; Fri, 23 Aug 2002 23:22:10 +0200 (CEST) (envelope-from phk@critter.freebsd.dk) To: Luigi Rizzo Cc: current@FreeBSD.ORG Subject: Re: how to compute the skew between TSC in SMP systems ? In-Reply-To: Your message of "Fri, 23 Aug 2002 14:13:14 PDT." <20020823141314.A82172@iguana.icir.org> Date: Fri, 23 Aug 2002 23:22:10 +0200 Message-ID: <30323.1030137730@critter.freebsd.dk> From: Poul-Henning Kamp Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG In message <20020823141314.A82172@iguana.icir.org>, Luigi Rizzo writes: >On Fri, Aug 23, 2002 at 11:02:29PM +0200, Poul-Henning Kamp wrote: >> In message <20020823134410.A81962@iguana.icir.org>, Luigi Rizzo writes: >> >Hi, >> >does anyone have an idea on how to determine the skew between >> >TSC content in the various processors on an SMP box ? >> >> On i386: It cannot be reliably done. Been there, tried that. > >the problem being what, too much jitter e.g. in measurement method >that i suggested or something similar ? Do you know what >kind of error you can get away with ? Much better: You tell me what you are trying to do, and I will tell you ways you can attempt it. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message