Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934856AbaGPG7N (ORCPT ); Wed, 16 Jul 2014 02:59:13 -0400 Received: from www.linutronix.de ([62.245.132.108]:53390 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932812AbaGPG7K (ORCPT ); Wed, 16 Jul 2014 02:59:10 -0400 Date: Wed, 16 Jul 2014 08:59:07 +0200 (CEST) From: Thomas Gleixner To: John Stultz cc: Miroslav Lichvar , LKML , Richard Cochran , Prarit Bhargava Subject: Re: [PATCH 0/3] timekeeping: Improved NOHZ frequency steering (v2) In-Reply-To: <53C5F95E.6010300@linaro.org> Message-ID: References: <1400288204-414-1-git-send-email-john.stultz@linaro.org> <20140519101439.GE4060@localhost> <20140708110816.GB23173@localhost> <53C5F95E.6010300@linaro.org> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 15 Jul 2014, John Stultz wrote: > On 07/08/2014 04:08 AM, Miroslav Lichvar wrote: > > On Mon, May 19, 2014 at 10:57:29AM -0700, John Stultz wrote: > >> Another area we have to be careful with is there are still > >> architectures (powerpc and ia64) which haven't switched from the old > >> vsyscall rounding logic (CONFIG_GENERIC_TIME_VSYSCALL_OLD). In these > >> cases we add up to 1ns of error each tick/update as we round up the > >> sub-nanoseconds to ensure we don't see inconsistencies. If the > >> adjustment logic can't handle this, I don't want to regress those > >> arches. > > I spent some time trying to figure out a workaround for the nanosecond > > rounding, but I didn't find anything that wouldn't complicate the mult > > adjustment logic and bring back the problems which the direct division > > approach is supposed to solve. > > > > It seems it may be a while before the old vsyscalls are fixed. How > > about including only the first two patches from this set for now? > > Hey! Sorry for the slow response here, I was on the road the last two weeks. > > So thanks for the ping here. If you're happy with the first two as an > initial step, I'd be willing to try to push those in. The only trouble > is there's a whole lot of timekeeping churn headed for 3.17 that Thomas > has cooked up. While there isn't likely to be direct conflicts in the > changes, I get nervous about mixing too many changes in subtle code at once. > > But maybe I'm being overly cautious? > > Thomas: Would you be ok if I push you some patches to improve ntp/ptp > freq steering w/ NOHZ for this merge window as well? So far the patches > have only shown nice improvements and no regressions, but its clearly > subtle code, and there's a lot going on in this merge window. I think it's ok. The steering is orthogonal to the other stuff cooking. Thanks, tglx -- 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/