Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1945901AbWBOJVz (ORCPT ); Wed, 15 Feb 2006 04:21:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1945902AbWBOJVz (ORCPT ); Wed, 15 Feb 2006 04:21:55 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:53710 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S1945901AbWBOJVy (ORCPT ); Wed, 15 Feb 2006 04:21:54 -0500 Date: Wed, 15 Feb 2006 10:19:59 +0100 From: Ingo Molnar To: Roman Zippel Cc: Andrew Morton , Thomas Gleixner , linux-kernel@vger.kernel.org, John Stultz Subject: Re: [patch] hrtimer: round up relative start time on low-res arches Message-ID: <20060215091959.GB1376@elte.hu> References: <1139827927.4932.17.camel@localhost.localdomain> <20060214074151.GA29426@elte.hu> <20060214122031.GA30983@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: -2.2 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.2 required=5.9 tests=ALL_TRUSTED,AWL autolearn=no SpamAssassin version=3.0.3 -2.8 ALL_TRUSTED Did not pass through any untrusted hosts 0.6 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1362 Lines: 29 * Roman Zippel wrote: > On Tue, 14 Feb 2006, Ingo Molnar wrote: > > > CONFIG_TIME_LOW_RES is a temporary way for architectures to signal that > > they simply return xtime in do_gettimeoffset(). In this corner-case we > > want to round up by resolution when starting a relative timer, to avoid > > short timeouts. This will go away with the GTOD framework. > > This fixes the worst cases. Even the common case should somehow > reflect that the relative start time should be rounded up in the same > way (even if not by that much), e.g. due to rounding the current > get_time() (at least for the non TIME_INTERPOLATION case) has a 1usec > resolution, which should be added there. yeah, agreed. That will be accurately fixed via GTOD's per-hwclock resolution values. It will have another advantage as well: e.g. the whole of m68k wont be penalized via CONFIG_TIME_LOW_RES for having a handful of sub-arches (Apollo, Sun3x, Q40) that dont have a higher resolution timer - every clock can define its own resolution. You could help that effort by porting m68k to use GTOD ;-) Ingo - 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/