From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261799AbVGGBOH (ORCPT ); Wed, 6 Jul 2005 21:14:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261801AbVGGBNz (ORCPT ); Wed, 6 Jul 2005 21:13:55 -0400 Received: from smtp.osdl.org ([65.172.181.4]:45227 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S261799AbVGGBNJ (ORCPT ); Wed, 6 Jul 2005 21:13:09 -0400 Date: Wed, 6 Jul 2005 18:12:20 -0700 From: Andrew Morton To: Dave Jones Cc: davem@davemloft.net, pmarques@grupopie.com, linux-kernel@vger.kernel.org Subject: Re: Slowdown with randomize_va_space in 2.6.12.2 Message-Id: <20050706181220.3978d7f6.akpm@osdl.org> In-Reply-To: <20050706205315.GC27630@redhat.com> References: <42CBE97C.2060208@grupopie.com> <20050706.125719.08321870.davem@davemloft.net> <20050706205315.GC27630@redhat.com> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Dave Jones wrote: > > On Wed, Jul 06, 2005 at 12:57:19PM -0700, David S. Miller wrote: > > From: Paulo Marques > > Date: Wed, 06 Jul 2005 15:23:56 +0100 > > > > > What is weird is that most of the extra time is being accounted as > > > user-space time, but the user-space application is exactly the same in > > > both runs, only the "randomize_va_space" parameter changed. > > > > It might be attributable to more cpu cache misses in userspace since > > the virtual addresses of everything are changing each and every > > invocation. > > On Transmeta CPUs that probably triggers a retranslation of > x86->native bytecode, if it thinks it hasn't seen code at that > address before. > ouch. What do we do? Default to off? Default to off on xmeta?