Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933493AbaGPMaG (ORCPT ); Wed, 16 Jul 2014 08:30:06 -0400 Received: from smtprelay02.ispgateway.de ([80.67.31.40]:40777 "EHLO smtprelay02.ispgateway.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933140AbaGPMaD (ORCPT ); Wed, 16 Jul 2014 08:30:03 -0400 X-Greylist: delayed 3337 seconds by postgrey-1.27 at vger.kernel.org; Wed, 16 Jul 2014 08:30:03 EDT Message-ID: <53C6633D.9080905@ladisch.de> Date: Wed, 16 Jul 2014 13:34:21 +0200 From: Clemens Ladisch User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Thomas Gleixner , Stefan Richter CC: linux-kernel@vger.kernel.org, linux1394-devel@lists.sourceforge.net, Peter Zijlstra , John Stultz Subject: Re: firewire: CLOCK_MONOTONIC_RAW exposure References: In-Reply-To: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Df-Sender: bGludXgta2VybmVsQGNsLmRvbWFpbmZhY3Rvcnkta3VuZGUuZGU= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thomas Gleixner wrote: > I wonder why firewire exposed CLOCK_MONOTONIC_RAW to user space. > > What's the purpose of that? CLOCK_MONOTONIC_RAW is the raw time based > on the initial frequency setup of the clocksource. That can be quite > off from the NTP corrected frequency which is exposed by > CLOCK_MONOTONIC. The purpose is to get a stable clock, i.e., to avoid clock rate changes caused by NTP corrections. ALSA is adding CLOCK_MONOTONIC_RAW for the same reason. Regards, Clemens -- 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/