From owner-freebsd-amd64@FreeBSD.ORG Tue Mar 14 11:49:32 2006 Return-Path: X-Original-To: freebsd-amd64@freebsd.org Delivered-To: freebsd-amd64@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8E33616A422 for ; Tue, 14 Mar 2006 11:49:32 +0000 (UTC) (envelope-from ray@redshift.com) Received: from mail-fs2.redshift.com (mail5.redshift.com [216.228.2.126]) by mx1.FreeBSD.org (Postfix) with ESMTP id 64E8E43D70 for ; Tue, 14 Mar 2006 11:49:27 +0000 (GMT) (envelope-from ray@redshift.com) Received: (qmail 16571 invoked by uid 89); 14 Mar 2006 11:49:25 -0000 Received: by simscan 1.2.0 ppid: 16566, pid: 16567, t: 0.0863s scanners: attach: 1.2.0 clamav: 0.88/m:36/d:1318 Received: from unknown (HELO workstation) (216.228.19.21) by mail-fs2.redshift.com with SMTP; 14 Mar 2006 11:49:25 -0000 Message-Id: <3.0.1.32.20060314034932.00ae9678@pop.redshift.com> X-Mailer: na X-Sender: redshift.com Date: Tue, 14 Mar 2006 03:49:32 -0800 To: kono@kth.se,JoaoBR From: ray@redshift.com In-Reply-To: <200603141238.26235.kono@kth.se> References: <200603140740.38388.joao@matik.com.br> <20060313221836.5491916A420@hub.freebsd.org> <200603141106.13693.kono@kth.se> <200603140740.38388.joao@matik.com.br> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: freebsd-amd64@freebsd.org Subject: Re: amd64 slower than i386 on identical AMD 64 system? X-BeenThere: freebsd-amd64@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Porting FreeBSD to the AMD64 platform List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 14 Mar 2006 11:49:32 -0000 At 12:38 PM 3/14/2006 +0100, Alexander Konovalenko wrote: | On Tuesday 14 March 2006 11:40, JoaoBR wrote: | > | > so where is your comparism? My point was that the same hardware is faster | > running i386 | > | > I experience this also on X2 machines but do not have two machines to | > compare I have a X2-4400-SMP running amd64 and a X2-4200-SMP running i386 | > and it gives me the same numbers running ubench | > | | I have experienced that -O3 and -ffast-math optimizations flags on AMD64 might | cause degrade in performance, meaning that -O2 is the fastest. When you | compile your ports what opt. flags do you use? Try to reinstall ubench with | different flags. Also code produced with gcc4.x is faster then system | compiler and has no degrade effect. Some time ago I was interested in fast | scientific computations and did some primitive benchmark tests | (http://daemon.nanophys.kth.se/~kono/testfcpu) | | I just wonder what will happen if you run ubench (compiled for i386) on AMD64, | will performance overcome amd64 ubench? | | | | /Alexander Konovalenko +2 cents mode on... :) I'm just coming in on the tail end of the message (missed the previous stuff). I recently did some benchmarks between AMD64 and i386 (version 5.4) on the same hardware. I initially saw that the i386 ran faster also. However, after searching a bit further, I discovered that I had made an error: the i386 kernel has the SMP stuff compiled into the generic kernel by default, while the AMD64 (at least on 5.4) does not. It has a separate kernel file called SMP (as I recall), which adds the SMP line and then does an include for the rest of the generic kernel config file (or something to that effect). Anyway, if you are testing back and forth, it's easy to forget that and end up accidently testing an i386 with SMP against an AMD64 without SMP. Like I say, I'm coming in on the tail end of the thread, so I might be off base, but it might be something worth double checking - just to be 100% sure. :-) Ray