From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932564AbWGBBDt (ORCPT ); Sat, 1 Jul 2006 21:03:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932577AbWGBBDt (ORCPT ); Sat, 1 Jul 2006 21:03:49 -0400 Received: from liaag2aa.mx.compuserve.com ([149.174.40.154]:46250 "EHLO liaag2aa.mx.compuserve.com") by vger.kernel.org with ESMTP id S932564AbWGBBDt (ORCPT ); Sat, 1 Jul 2006 21:03:49 -0400 Date: Sat, 1 Jul 2006 20:57:13 -0400 From: Chuck Ebbert <76306.1226@compuserve.com> Subject: Re: [patch 0/2] sLeAZY FPU feature To: Arjan van de Ven Cc: Andrew Morton , linux-kernel , Andi Kleen , Nick Piggin Message-ID: <200607012058_MC3-1-C3F3-F21@compuserve.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In-Reply-To: <1151782942.3195.56.camel@laptopd505.fenrus.org> On Sat, 01 Jul 2006 21:42:22 +0200, Arjan van de Ven wrote: > > What sort of test? > > the one I did was long running FPU app (calculating PI using FPU) Mine was just running a program that loops doing getpid() in one window and this in another: #define _GNU_SOURCE #include #include #define rdtscll(t) asm("rdtsc" : "=A" (t)) int main(int argc, char * const argv[]) { long long tsc1, tsc2; long double ld = 0.0; int i, iters = 999999999; rdtscll(tsc1); for (i = 0; i < iters; i++) ld += 1.0; rdtscll(tsc2); printf("count: %Lf, clocks: %llu\n", ld, tsc2 - tsc1); return 0; } So the ~0.4% gain I saw (averaging 10 tests) was likely the minimum and Arjan's 8.5% gain when switching tasks after every FPU operation is the max. -- Chuck "You can't read a newspaper if you can't read." --George W. Bush