From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753787Ab2LSS2l (ORCPT ); Wed, 19 Dec 2012 13:28:41 -0500 Received: from mail-ie0-f171.google.com ([209.85.223.171]:49978 "EHLO mail-ie0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752412Ab2LSS2d (ORCPT ); Wed, 19 Dec 2012 13:28:33 -0500 Message-ID: <50D2074D.4000101@linaro.org> Date: Wed, 19 Dec 2012 10:28:29 -0800 From: John Stultz User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Bernd Faust CC: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Subject: Re: [PATCH] Round the calculated scale factor in set_cyc2ns_scale() References: <1354717009-2687-1-git-send-email-berndfaust@gmail.com> In-Reply-To: <1354717009-2687-1-git-send-email-berndfaust@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/05/2012 06:16 AM, Bernd Faust wrote: > During some experiments with an external clock (in a FPGA), we saw that > the TSC clock drifted approx. 2.5ms per second. > > This drift was caused by the current way of calculating the scale. > In our case cpu_khz had a value of 3292725. This resulted in a scale > value of 310. But when doing the calculation by hand it shows that the > actual value is 310.9886188491, so a value of 311 would be more precise. > > With this change the value is rounded. > > Signed-off-by: Bernd Faust Thanks for sending this in! I've queued it, but because I was slow here, it will have to wait for 3.9. Sorry for the delay, and thanks again! -john