From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261831AbVFUOzs (ORCPT ); Tue, 21 Jun 2005 10:55:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261980AbVFUOzs (ORCPT ); Tue, 21 Jun 2005 10:55:48 -0400 Received: from zcars04f.nortelnetworks.com ([47.129.242.57]:40657 "EHLO zcars04f.nortelnetworks.com") by vger.kernel.org with ESMTP id S261831AbVFUOzn (ORCPT ); Tue, 21 Jun 2005 10:55:43 -0400 Message-ID: <42B82A4F.5090804@nortel.com> Date: Tue, 21 Jun 2005 08:55:11 -0600 X-Sybari-Space: 00000000 00000000 00000000 00000000 From: Chris Friesen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040115 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Lee Revell CC: john stultz , Roman Zippel , lkml , Andrew Morton , George Anzinger , Ulrich Windl Subject: Re: [PATCH 1/6] new timeofday core subsystem for -mm (v.B3) References: <1119063400.9663.2.camel@cog.beaverton.ibm.com> <1119287354.9947.22.camel@cog.beaverton.ibm.com> <1119291034.16180.9.camel@mindpipe> <1119304422.9947.90.camel@cog.beaverton.ibm.com> <1119311096.17701.3.camel@mindpipe> In-Reply-To: <1119311096.17701.3.camel@mindpipe> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Lee Revell wrote: > But some user space apps are now *required* to use rdtsc for timing due > to the massive performance difference. If we only took a 5x or 10x > performance hit vs rdtsc, rather than the current 50x, it might be > enough that user space apps won't have to do this. For my userspace apps I've actually switched to clock_gettime(CLOCK_MONOTONIC, &ts); This at least guarantees that it will never go backwards. For the experts: Is there a clock exported to userspace that is both monotonic and uniform? Does CLOCK_MONOTONIC give this on linux? Chris