Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261703AbVAYATT (ORCPT ); Mon, 24 Jan 2005 19:19:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261735AbVAYAG1 (ORCPT ); Mon, 24 Jan 2005 19:06:27 -0500 Received: from e33.co.us.ibm.com ([32.97.110.131]:35731 "EHLO e33.co.us.ibm.com") by vger.kernel.org with ESMTP id S261752AbVAYADn (ORCPT ); Mon, 24 Jan 2005 19:03:43 -0500 Subject: Re: [RFC][PATCH] new timeofday core subsystem (v. A2) From: john stultz To: Christoph Lameter Cc: lkml , Tim Schmielau , George Anzinger , albert@users.sourceforge.net, Ulrich Windl , Dominik Brodowski , David Mosberger , Andi Kleen , paulus@samba.org, schwidefsky@de.ibm.com, keith maanthey , Patricia Gaughen , Chris McDermott , Max Asbock , mahuja@us.ibm.com, Nishanth Aravamudan , Darren Hart , "Darrick J. Wong" , Anton Blanchard In-Reply-To: References: <1106607089.30884.10.camel@cog.beaverton.ibm.com> Content-Type: text/plain Date: Mon, 24 Jan 2005 16:03:36 -0800 Message-Id: <1106611416.30884.22.camel@cog.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.0.2 (2.0.2-3) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1278 Lines: 36 On Mon, 2005-01-24 at 15:24 -0800, Christoph Lameter wrote: > On Mon, 24 Jan 2005, john stultz wrote: > > + /* convert to nanoseconds */ > > + ns_offset = cyc2ns(timesource, delta, NULL); > > + > > + /* apply the NTP scaling */ > > + ns_offset = ntp_scale(ns_offset); > > The monotonic clock is the time base for the gettime and gettimeofday > functions. This means ntp_scale() is called every time that the kernel or > an application access time. > > As pointed out before this will dramatically worsen the performance > compared to the current code base. > > ntp_scale() also will make it difficult to implement optimized arch > specific version of function for timer access. > > The fastcalls would have to be disabled on ia64 to make this work. Its > likely extremely difficult to implement a fastcall if it involves > ntp_scale(). Yep, performance is a big concern. Re-working ntp_scale() is still on my TODO list. I just didn't get to it in this release. Patches are always welcome. :) thanks for the feedback! -john - 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/