From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764289AbXGPAde (ORCPT ); Sun, 15 Jul 2007 20:33:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760245AbXGPAd0 (ORCPT ); Sun, 15 Jul 2007 20:33:26 -0400 Received: from one.firstfloor.org ([213.235.205.2]:56528 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760243AbXGPAdZ (ORCPT ); Sun, 15 Jul 2007 20:33:25 -0400 Date: Mon, 16 Jul 2007 02:33:22 +0200 From: Andi Kleen To: Mathieu Desnoyers Cc: Alexey Dobriyan , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Adrian Bunk , Andi Kleen Subject: Re: [patch 4/8] Immediate Value - Add kconfig menus Message-ID: <20070716003322.GA26835@one.firstfloor.org> References: <20070714012439.285079881@polymtl.ca> <20070714012623.839969254@polymtl.ca> <20070714072801.GB5822@martell.zuzino.mipt.ru> <20070714152734.GB4737@Krystal> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070714152734.GB4737@Krystal> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > On embedded systems, the tradeoff is not the same. The immediate values > trade a little bit of system memory (to keep the pointers to the > variable and instruction as well as the size of the variable, only used > when the variable is updated) in order to remove cache line hot paths. Please remove the Kconfig. I don't think it makes sense. Such optimizations should be always enabled. We don't have CONFIG_GO_FASTER configs normally. Don't introduce them now. > > Also, embedded systems with physically read-only memory clearly does not > want to enable this. We always patch the x86 kernel, so they have to deal with it anyways. The x86 port doesn't support XIP. -Andi