Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754872AbYFKVJk (ORCPT ); Wed, 11 Jun 2008 17:09:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751741AbYFKVJc (ORCPT ); Wed, 11 Jun 2008 17:09:32 -0400 Received: from mx2.compro.net ([216.54.166.4]:60028 "EHLO mx2.compro.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750977AbYFKVJb (ORCPT ); Wed, 11 Jun 2008 17:09:31 -0400 X-IronPort-AV: E=Sophos;i="4.27,626,1204520400"; d="scan'208";a="2334484" Message-ID: <48503EB9.6000606@compro.net> Date: Wed, 11 Jun 2008 17:08:09 -0400 From: Mark Hounschell Reply-To: markh@compro.net Organization: Compro Computer Svcs. User-Agent: Thunderbird 2.0.0.9 (X11/20070801) MIME-Version: 1.0 To: Arjan van de Ven CC: "linux-os (Dick Johnson)" , Jan Engelhardt , "Kok, Auke" , "solsTiCe d'Hiver" , linux-kernel@vger.kernel.org Subject: Re: PROBLEM: no cpu MHz in /proc/cpuinfo on 2.6.25.4-rt6 References: <200806102152.23286.solstice.dhiver@gmail.com> <20080610131314.5f7069e6@infradead.org> <484EE71A.40002@intel.com> <20080611063639.5e1eea5b@infradead.org> <20080611065816.6cff290d@infradead.org> <20080611083644.32afc823@infradead.org> <4850046C.4070602@compro.net> <20080611104446.3b0ce2d9@infradead.org> <48501159.4050908@compro.net> <48503792.50003@compro.net> <20080611135828.29f6a7d7@infradead.org> In-Reply-To: <20080611135828.29f6a7d7@infradead.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1078 Lines: 32 Arjan van de Ven wrote: > On Wed, 11 Jun 2008 16:37:38 -0400 > Mark Hounschell wrote: > >>> Mark >>> >> Ok, what would one use besides the tsc to take a fast high-res time >> stamp in a kernel module that could also be used in user land (same >> time source) to for instance calculate the the time between an event >> in the kernel to an event in user land? >> >> do_gettimeofday / gettimeofday are not really acceptable. > > > btw you also changed the problem from "what is the cpu frequency" to > "how usable is rdtsc for time". My entire point was that these weren't > related... > > If they are not the same how do you know at what rate the tsc is counting. But back to "how usable is rdtsc for time", is there a clock_gettime(CLOCK_MONOTONIC, &time) equivalent that can be used in the kernel? Mark -- 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/