From owner-cvs-all Thu Feb 6 14: 4:54 2003 Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7792637B401; Thu, 6 Feb 2003 14:04:52 -0800 (PST) Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.86.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9AFE443FA3; Thu, 6 Feb 2003 14:04:51 -0800 (PST) (envelope-from phk@freebsd.org) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.12.6/8.12.6) with ESMTP id h16M4hqV002856; Thu, 6 Feb 2003 23:04:44 +0100 (CET) (envelope-from phk@freebsd.org) To: Peter Wemm Cc: Bruce Evans , "Greg 'groggy' Lehey" , all-committers@freebsd.org, legacy-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/i386/include clock.h src/sys/i386/i386 tsc.c From: phk@freebsd.org In-Reply-To: Your message of "Thu, 06 Feb 2003 14:02:09 PST." <20030206220209.EDA882A89E@canning.wemm.org> Date: Thu, 06 Feb 2003 23:04:43 +0100 Message-ID: <2855.1044569083@critter.freebsd.dk> Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG In message <20030206220209.EDA882A89E@canning.wemm.org>, Peter Wemm writes: >phk@freebsd.org wrote: >> In message <20030206174018.R72201-100000@gamplex.bde.org>, Bruce Evans writes > : >> >> >However, precise measurements of these clocks turn out to be essentially >> >useless except probably for phk's nonstandard hardware, since the >> >accuracy of these clocks is much worse than their precision. Drift of >> >10-100 parts per million for a 10 degree temperature change is normal. >> >So calibrations more precise than this are not useful. >> >> Actually, things have improved, and motherboard crystals are now >> generally no worse than +/-1 PPM/K. > >For newer motherboards. :-) I think for anything after PII, it was the new clock regime which put tighter limits on jitter that did it I think. -- 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 cvs-all" in the body of the message