From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261872AbTDPXMJ (ORCPT ); Wed, 16 Apr 2003 19:12:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261876AbTDPXMJ (ORCPT ); Wed, 16 Apr 2003 19:12:09 -0400 Received: from e35.co.us.ibm.com ([32.97.110.133]:57500 "EHLO e35.co.us.ibm.com") by vger.kernel.org with ESMTP id S261872AbTDPXMI (ORCPT ); Wed, 16 Apr 2003 19:12:08 -0400 Subject: Re: [PATCH] linux-2.5.67_lost-tick-fix_A2 From: john stultz To: george anzinger Cc: Andrew Morton , lkml , James.Bottomley@SteelEye.com, shemminger@osdl.org, alex@ssi.bg In-Reply-To: <3E9DE126.7040001@mvista.com> References: <1050530545.1077.120.camel@w-jstultz2.beaverton.ibm.com> <3E9DE126.7040001@mvista.com> Content-Type: text/plain Organization: Message-Id: <1050535296.1077.204.camel@w-jstultz2.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.4 Date: 16 Apr 2003 16:21:36 -0700 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2003-04-16 at 16:03, george anzinger wrote: > john stultz wrote: > > Some of the divs and mods being added here might concern folks, but by > > not calling timer->get_offset() in detect_lost_tick() we eliminate much > > of the same math. I did some simple cycle counting and the new code > > comes out on average equivalent or faster. > > I think that if you look at the generated code you may find that there > are NO div in the asm code. The C folks know about scaling to avoid > div especially when the divisor is a constant :) Indeed you are correct. An objdump of both the timer_tsc.o and timer_cyclone.o code reveals that the only divs occur in init code. I like your argument better then mine :) thanks -john