From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists.gentoo.org ([140.105.134.102] helo=robin.gentoo.org) by nuthatch.gentoo.org with esmtp (Exim 4.50) id 1ES1ts-0006f2-1Z for garchives@archives.gentoo.org; Wed, 19 Oct 2005 00:33:48 +0000 Received: from robin.gentoo.org (localhost [127.0.0.1]) by robin.gentoo.org (8.13.5/8.13.5) with SMTP id j9J0TgLc003089; Wed, 19 Oct 2005 00:29:42 GMT Received: from vms048pub.verizon.net (vms048pub.verizon.net [206.46.252.48]) by robin.gentoo.org (8.13.5/8.13.5) with ESMTP id j9J0TfCR011573 for ; Wed, 19 Oct 2005 00:29:42 GMT Received: from gw.thefreemanclan.net ([151.201.145.103]) by vms048.mailsrvcs.net (Sun Java System Messaging Server 6.2 HotFix 0.04 (built Dec 24 2004)) with ESMTPA id <0IOK00CH1ZZ95GD2@vms048.mailsrvcs.net> for gentoo-amd64@lists.gentoo.org; Tue, 18 Oct 2005 19:28:22 -0500 (CDT) Received: by gw.thefreemanclan.net (Postfix, from userid 81) id 9572351845F; Tue, 18 Oct 2005 20:28:21 -0400 (EDT) Received: from 202.248.61.99 (SquirrelMail authenticated user rich) by gw.thefreemanclan.net with HTTP; Tue, 18 Oct 2005 20:28:21 -0400 (EDT) Date: Tue, 18 Oct 2005 20:28:21 -0400 (EDT) From: "Richard Freeman" Subject: Re: [gentoo-amd64] Clock skew In-reply-to: <43557f52.553fc4@vuk.kjorling.com> To: gentoo-amd64@lists.gentoo.org Message-id: <14956.202.248.61.99.1129681701.squirrel@gw.thefreemanclan.net> Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-amd64@gentoo.org Reply-to: gentoo-amd64@lists.gentoo.org MIME-version: 1.0 Content-type: text/plain; charset=iso-8859-1 Content-transfer-encoding: 8bit Importance: Normal X-Priority: 3 (Normal) References: <2df021250510181514m205a3b42m4eb4ed0c099c89e2@mail.gmail.com> <43557684.da9a98d@vuk.kjorling.com> <43557CF7.8060404@flashtek-uk.com> <43557f52.553fc4@vuk.kjorling.com> User-Agent: SquirrelMail/1.4.5 X-Archives-Salt: 6571f9a1-43c2-48ef-be48-a04e06a13367 X-Archives-Hash: 0380070cf348cb01970188d0632e6bb9 On Tue, October 18, 2005 7:03 pm, Michael Kjorling wrote: > So they say, but I'd be careful with running ntpdate from a cron job. > I recall a recent discussion (think it was on linux@yahoogroups.com, > but could be wrong) where one person was having real trouble because > of it resetting the system clock. When he converted to running ntpd > instead, the problem disappeared. > Hmm, my guess (somewhat educated) is that ntpdate is abruptly changing the clock, while ntpd normally just slews the clock by adjusting the timer settings. This means that every second on the clock still ticks with ntpd, but not with ntpdate. That probably has a big impact on anything that uses real-time-clock scheduling - especially if you're running ntpdate once a minute or something like that. I'm not sure how multimedia works in linux - it may not use the system clock for timing. If it did I could definintely see issues happening if buffers run out or if video/audio get out of sync. I personally just let leave the RTC on GMT and run ntpd. It is mostly fire-and-forget. As others have pointed out though, it doesn't handle clock slews this large easily (maybe there is a parameter or source-code-constant that can be tweaked to compensate). -- gentoo-amd64@gentoo.org mailing list