Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750769AbWLMUoP (ORCPT ); Wed, 13 Dec 2006 15:44:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750794AbWLMUoP (ORCPT ); Wed, 13 Dec 2006 15:44:15 -0500 Received: from scrub.xs4all.nl ([194.109.195.176]:40646 "EHLO scrub.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750769AbWLMUoO (ORCPT ); Wed, 13 Dec 2006 15:44:14 -0500 Date: Wed, 13 Dec 2006 21:40:34 +0100 (CET) From: Roman Zippel X-X-Sender: roman@scrub.home To: john stultz cc: Ingo Molnar , Thomas Gleixner , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [RFC] HZ free ntp In-Reply-To: <1166037549.6425.21.camel@localhost.localdomain> Message-ID: References: <20061204204024.2401148d.akpm@osdl.org> <20061205203013.7073cb38.akpm@osdl.org> <1165393929.24604.222.camel@localhost.localdomain> <20061206131155.GA8558@elte.hu> <1165956021.20229.10.camel@localhost> <1166037549.6425.21.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1720 Lines: 45 Hi, On Wed, 13 Dec 2006, john stultz wrote: > > The largest possible interval is freq cycles (or 1 second without > > adjustments). That is the base interval and without redesigning NTP we > > can't change that. This base interval can be subdivided into smaller > > intervals for incremental updates. > > Indeed, larger then 1 second intervals would require the second_overflow > code to be reworked too. There isn't much to rework without a complete redesign. > > You cannot choose arbitrary intervals otherwise you get other problems, > > e.g. with your patch time_offset handling is broken. > > I'm not seeing this yet. Any more details? time_offset is scaled to HZ in do_adjtimex, which needs to be changed as well. > > You don't have to introduce anything new, it's tick_length that changes > > and HZ that becomes a variable in this function. > > So, forgive me for rehashing this, but it seems we're cross talking > again. The context here is the dynticks code. Where HZ doesn't change, > but we get interrupts at much reduced rates. I know and all you have to change in the ntp and some related code is to replace HZ there with a variable, thus make it changable, so you can increase the update interval (i.e. it becomes 1s/hz instead of 1s/HZ). > However, in doing so we have to > work w/ the ntp.c code which (as Ingo earlier mentioned) has a number of > HZ based assumptions. Repeating Ingo's nonsense doesn't make it any more true. :-( bye, Roman - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/