From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758009Ab3DAUlf (ORCPT ); Mon, 1 Apr 2013 16:41:35 -0400 Received: from mail-pb0-f44.google.com ([209.85.160.44]:59897 "EHLO mail-pb0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756796Ab3DAUle (ORCPT ); Mon, 1 Apr 2013 16:41:34 -0400 Message-ID: <5159F0FA.40306@linaro.org> Date: Mon, 01 Apr 2013 13:41:30 -0700 From: John Stultz User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130308 Thunderbird/17.0.4 MIME-Version: 1.0 To: Pavel Machek CC: "Rafael J. Wysocki" , Feng Tang , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Len Brown , linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 0/5] Add support for S3 non-stop TSC support. References: <1358750325-21217-1-git-send-email-feng.tang@intel.com> <50FD48B6.9010202@intel.com> <20130330181451.GF28947@amd.pavel.ucw.cz> <5159C4AE.2050504@linaro.org> <20130401203136.GA2543@amd.pavel.ucw.cz> In-Reply-To: <20130401203136.GA2543@amd.pavel.ucw.cz> 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 04/01/2013 01:31 PM, Pavel Machek wrote: > > Certainly for short sleeps. Is TSC actually precise enough to keep > precise time for hours? I thought TSC sucked at precision. Well, we can measure suspend using the ntp corrected frequency, so that should be ok, assuming the freq doesn't change during suspend. But yes, the long term accuracy will depend on the actual hardware implementation, so we'll have to see what the hardware does. Even so, other boards have similar non-stop clocksources in suspend that could be used in a similar fashion, so I think this is still the right appraoch. thanks -john