From owner-freebsd-arch Mon Oct 29 21:26:32 2001 Delivered-To: freebsd-arch@freebsd.org Received: from rover.village.org (rover.bsdimp.com [204.144.255.66]) by hub.freebsd.org (Postfix) with ESMTP id 9A49237B403 for ; Mon, 29 Oct 2001 21:26:29 -0800 (PST) Received: from harmony.village.org (harmony.village.org [10.0.0.6]) by rover.village.org (8.11.3/8.11.3) with ESMTP id f9U5QSV02539 for ; Mon, 29 Oct 2001 22:26:28 -0700 (MST) (envelope-from imp@harmony.village.org) Received: from harmony.village.org (localhost [127.0.0.1]) by harmony.village.org (8.11.6/8.11.6) with ESMTP id f9U5QR701909 for ; Mon, 29 Oct 2001 22:26:27 -0700 (MST) (envelope-from imp@harmony.village.org) Message-Id: <200110300526.f9U5QR701909@harmony.village.org> Subject: Re: 64 bit times revisited.. To: arch@FreeBSD.ORG In-reply-to: Your message of "Mon, 29 Oct 2001 22:09:26 MST." <200110300509.f9U59Q701756@harmony.village.org> References: <200110300509.f9U59Q701756@harmony.village.org> <613.1004134852@critter.freebsd.dk> Date: Mon, 29 Oct 2001 22:26:27 -0700 From: Warner Losh Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG In message <200110300509.f9U59Q701756@harmony.village.org> Warner Losh writes: : Xtals in PCs SUCKSUCKSUCKSUCK. They are accurate to a factor of 1E-8 : or so. This is >> 1/(2^64). When something drifts a second or two a : day (or even a week or a month), you know it is really bad. I forgot the punchline: The error from the variance in your xtal is so far going to swamp the error from rounding for 1/(2^64) that it isn't a reason to not do it. After reading the thread, people seem to be under the impression that the xtals in PCs are consistant or stable. They are neither by any stretch of the imagination. There may be other reasons to not do this, but this isn't one. :-) Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message