From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754138AbbAJCDh (ORCPT ); Fri, 9 Jan 2015 21:03:37 -0500 Received: from smtp.codeaurora.org ([198.145.11.231]:35844 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752716AbbAJCDg (ORCPT ); Fri, 9 Jan 2015 21:03:36 -0500 Message-ID: <54B08876.1040200@codeaurora.org> Date: Fri, 09 Jan 2015 18:03:34 -0800 From: Stephen Boyd User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: John Stultz , Linux Kernel Mailing List CC: Dave Jones , Linus Torvalds , Thomas Gleixner , Richard Cochran , Prarit Bhargava , Ingo Molnar , Peter Zijlstra Subject: Re: [PATCH 02/10] clocksource: Simplify logic around clocksource wrapping saftey margins References: <1420850068-27828-1-git-send-email-john.stultz@linaro.org> <1420850068-27828-3-git-send-email-john.stultz@linaro.org> In-Reply-To: <1420850068-27828-3-git-send-email-john.stultz@linaro.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/09/2015 04:34 PM, John Stultz wrote: > The clocksource logic has a number of places where we try to > include a safety margin. Most of these are 12% safety margins, > but they are inconsistently applied and sometimes are applied > on top of each other. > > Additionally, in the previous patch, we corrected an issue > where we unintentionally in effect created a 50% saftey margin, > which these 12.5% margins where then added to. > > So to siplify the logic here, this patch removes the various > 12.5% margins, and consolidates adding the margin in one place: > clocks_calc_max_nsecs(). > > Addtionally, Linus prefers a 50% safety margin, as it allows > bad clock values to be more easily caught. This should really > have no net effect, due to the corrected issue earlier which > caused greater then 50% margins to be used w/o issue. > > Cc: Dave Jones > Cc: Linus Torvalds > Cc: Thomas Gleixner > Cc: Richard Cochran > Cc: Prarit Bhargava > Cc: Stephen Boyd > Cc: Ingo Molnar > Cc: Peter Zijlstra > Signed-off-by: John Stultz > --- For sched_clock.c part Acked-by: Stephen Boyd -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project