From owner-freebsd-current Fri Aug 23 14:41:32 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 8D8F937B40C for ; Fri, 23 Aug 2002 14:41:22 -0700 (PDT) Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.86.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id A7A9543E65 for ; Fri, 23 Aug 2002 14:41:21 -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 g7NLbvoc030561; Fri, 23 Aug 2002 23:37:57 +0200 (CEST) (envelope-from phk@critter.freebsd.dk) To: John Polstra 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 14:35:35 PDT." <200208232135.g7NLZZqx088123@vashon.polstra.com> Date: Fri, 23 Aug 2002 23:37:57 +0200 Message-ID: <30560.1030138677@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 <200208232135.g7NLZZqx088123@vashon.polstra.com>, John Polstra write s: Still, the feature has come in handy when debugging certain >multiprocessor situations where I really needed to know the relative >ordering of events taking place on both CPUs. Right, you might get away with that in tightly controlled circumstances, but it would probably be far smarter to use the counter in the IOAPIC (exists on all SMP) or the ACPI counter even in such cases. -- 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