From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754923AbXABTqT (ORCPT ); Tue, 2 Jan 2007 14:46:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754935AbXABTqT (ORCPT ); Tue, 2 Jan 2007 14:46:19 -0500 Received: from e1.ny.us.ibm.com ([32.97.182.141]:43018 "EHLO e1.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754923AbXABTqR (ORCPT ); Tue, 2 Jan 2007 14:46:17 -0500 Subject: Re: [RFC] HZ free ntp From: john stultz To: Roman Zippel Cc: Ingo Molnar , Thomas Gleixner , Andrew Morton , linux-kernel@vger.kernel.org In-Reply-To: <200701011727.46944.zippel@linux-m68k.org> References: <20061204204024.2401148d.akpm@osdl.org> <1166578357.5594.3.camel@localhost> <200701011727.46944.zippel@linux-m68k.org> Content-Type: text/plain Date: Tue, 02 Jan 2007 11:42:12 -0800 Message-Id: <1167766932.3141.10.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.8.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2007-01-01 at 17:27 +0100, Roman Zippel wrote: > On Wednesday 20 December 2006 02:32, john stultz wrote: > > > > 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). > > > > Untested patch below. Does this vibe better with you are suggesting? > > Yes, thanks. > tick_nsec doesn't require special treatment, in the middle term it's obsolete > anyway, it could be replaced with (current_tick_length() >> > TICK_LENGTH_SHIFT) and current_tick_length() being inlined. If NTP_INTERVAL_FREQ is different then HZ, then tick_nsec still has a different meaning then (current_tick_length() >> TICK_LENGTH_SHIFT). So since tick_nsec is still used in quite a few places, so I'm hesitant to pull it. > NTP_INTERVAL_FREQ could be a real variable (so it can be initialized at > runtime), it's already gone from all important paths. Wait, so you're suggesting NTP_INTERVAL_FREQ be a dynamic variable instead of a constant? Curious, could you give a bit more detail on why? > In the short term I'd prefered a clock would store its frequency instead of > using NTP_INTERVAL_LENGTH in clocksource_calculate_interval(), so it doesn't > has to be derived there. I don't follow this at all. clocksources do store their own frequency (via mult/shift). Could you explain? thanks -john