From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754491Ab1JQWJj (ORCPT ); Mon, 17 Oct 2011 18:09:39 -0400 Received: from terminus.zytor.com ([198.137.202.10]:36840 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752939Ab1JQWJi (ORCPT ); Mon, 17 Oct 2011 18:09:38 -0400 Message-ID: <4E9CA772.4000509@zytor.com> Date: Mon, 17 Oct 2011 15:08:50 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0) Gecko/20110927 Thunderbird/7.0 MIME-Version: 1.0 To: Ingo Molnar CC: Thomas Gleixner , Linus Torvalds , Simon Kirby , Peter Zijlstra , Linux Kernel Mailing List , Dave Jones , Martin Schwidefsky Subject: Re: Linux 3.1-rc9 References: <1318060551.8395.0.camel@twins> <20111012213555.GC24461@hostway.ca> <20111013232521.GA5654@hostway.ca> <20111017045806.GA11561@elte.hu> <20111017184916.GA5545@elte.hu> <4E9C917B.2050802@zytor.com> <20111017211951.GA8043@elte.hu> <4E9C9CAE.9090207@zytor.com> <20111017213958.GA27126@elte.hu> In-Reply-To: <20111017213958.GA27126@elte.hu> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/17/2011 02:39 PM, Ingo Molnar wrote: >> >> We can do much better than that with reciprocal multiplication. > > Yes, 2^64/1e9 is the reciprocal. > What I mean is that it's pretty easy to work it so it doesn't have the errors. We have 32*32 = 64 multiplication on all 32-bit platforms I'm 99.9% sure. -hpa