From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262621AbULPCHq (ORCPT ); Wed, 15 Dec 2004 21:07:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262602AbULPCFY (ORCPT ); Wed, 15 Dec 2004 21:05:24 -0500 Received: from out006pub.verizon.net ([206.46.170.106]:52706 "EHLO out006.verizon.net") by vger.kernel.org with ESMTP id S262582AbULPB7z (ORCPT ); Wed, 15 Dec 2004 20:59:55 -0500 From: Gene Heskett Reply-To: gene.heskett@verizon.net Organization: Organization: None, detectable by casual observers To: linux-kernel@vger.kernel.org Subject: Re: USB making time drift [was Re: dynamic-hz] Date: Wed, 15 Dec 2004 20:59:52 -0500 User-Agent: KMail/1.7 Cc: Andrea Arcangeli , Pavel Machek , Zwane Mwaikambo , Con Kolivas References: <20041213002751.GP16322@dualathlon.random> <200412151144.38785.gene.heskett@verizon.net> <20041215182012.GH16322@dualathlon.random> In-Reply-To: <20041215182012.GH16322@dualathlon.random> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200412152059.52292.gene.heskett@verizon.net> X-Authentication-Info: Submitted using SMTP AUTH at out006.verizon.net from [151.205.42.94] at Wed, 15 Dec 2004 19:59:53 -0600 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 15 December 2004 13:20, Andrea Arcangeli wrote: >On Wed, Dec 15, 2004 at 11:44:38AM -0500, Gene Heskett wrote: >> The HZ=1000 is the culprit? > >HZ=1000 isn't the culprit. The culprit is the >1msec latency of the > usb irq, but that wouldn't be visible with HZ 100 (for this :> specific case HZ=100 would only be a band-aid). > >> Onboard AC-97 audio of course. Crappy stuff... [..] > >I doubt it's the chip, but only the motherboard to blame. My laptop > has the ac97 but no HZ sound out of it. > >> translate to 10 millisecond intervals. If you had a 4 millisecond >> latency, >> that would be spread over 4 of the 1000 hz interrupts. That >> sounds rather confusing to the service routine I imagine. > >The ones that get confused are the system time and the jiffies, the > rest of the system can deal with long irq delays. The tick > adjustment was exactly implemented so that the jiffies and system > time wouldn't get confused anymore, but it just confuses it the > other way around in my current experience. > >> I'll do that just for grins & report back. > >Ok. Unforch, I was not able to find that in the .config file, so where is that particular option set? -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) 99.30% setiathome rank, not too shabby for a WV hillbilly Yahoo.com attorneys please note, additions to this message by Gene Heskett are: Copyright 2004 by Maurice Eugene Heskett, all rights reserved.