Return-Path: Received: from Hermes.suse.de (Hermes.suse.de [10.10.96.4]) by Wotan.suse.de (Postfix) with ESMTP id C975A8509E for ; Wed, 14 Nov 2001 16:50:14 +0100 (CET) Received: by Hermes.suse.de (Postfix) id B3D265D848; Wed, 14 Nov 2001 16:50:14 +0100 (MET) Received: from Cantor.suse.de (ns.suse.de [213.95.15.193]) by Hermes.suse.de (Postfix) with ESMTP id 3DCEB5D852; Wed, 14 Nov 2001 16:50:14 +0100 (MET) Received: from vger.kernel.org (vger.kernel.org [199.183.24.194]) by Cantor.suse.de (Postfix) with ESMTP id 0401E1E44F; Wed, 14 Nov 2001 16:50:14 +0100 (MET) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 14 Nov 2001 10:38:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 14 Nov 2001 10:38:07 -0500 Received: from smtpde02.sap-ag.de ([194.39.131.53]:47523 "EHLO smtpde02.sap-ag.de") by vger.kernel.org with ESMTP id ; Wed, 14 Nov 2001 10:36:19 -0500 Received: from sap-ag.de (smtpde02) by smtpde02.sap-ag.de (out) with ESMTP id QAA13117; Wed, 14 Nov 2001 16:39:14 +0100 (MEZ) Message-ID: <3BF28F6C.90008@sap.com> Date: Wed, 14 Nov 2001 16:36:12 +0100 From: Willi =?ISO-8859-1?Q?N=FC=DFer?= Organization: SAP AG User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.5) Gecko/20011012 X-Accept-Language: en-us MIME-Version: 1.0 To: Brian Gerst Cc: lkml Subject: Re: Comparison of PAE and Non-PAE 2..4.14 (p8) in high load In-Reply-To: <3BF27557.30007@sap.com> <3BF2837B.4B63FBA5@didntduck.org> Content-Type: text/plain; charset=us-ascii; format=flowed X-SAP: out Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 7bit Brian Gerst wrote: >> >>Results: >>--------- >> >>2.4.7 >> 2.4.14p8 PAE 2.4.14p4 non- PAE >>------------------------------------------------------------- >> 1.80 13.42 15.47 >> 1.10 13.28 14.76 >> 1.20 14.08 14.63 >> 1.26 13.17 15.30 >> 1.35 13.41 14.51 >> >>This means that we did see a performance decrease of about >>6 % compared to 2.4.14p8 nonPAE but still 2.4.14p8 is an order >>of magnitude faster than 2.4.7 >> > > PAE mode increases the size of the page table entries to 64-bits, and > the x86 doesn't do 64-bit operations very well. Plus it has three > levels of tables to work with instead of two. Yes, I know the difference. The reason for this post was not blind curiosity but the presumption that the great performance increase of 2.4.14p8 we reported was mainly due to the PAE enabling in the 2.4.7 and non-PAE-enabling 2.4.14p8 in our first test. The tests above show that this is not the case. Even with PAE 2.4.14 is faster by an order of magnitude. The other info we did find interesting is the actual amount of difference between PAE and nonPAE. The 6% we got fit very well in some estimates I found on lkml. -- Best regards Willi ----------------------------------- Willi Nuesser SAP Linuxlab - 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/