Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753224AbZI1UhY (ORCPT ); Mon, 28 Sep 2009 16:37:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753033AbZI1UhX (ORCPT ); Mon, 28 Sep 2009 16:37:23 -0400 Received: from casper.infradead.org ([85.118.1.10]:59645 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753018AbZI1UhX (ORCPT ); Mon, 28 Sep 2009 16:37:23 -0400 Date: Mon, 28 Sep 2009 22:37:35 +0200 From: Arjan van de Ven To: Andi Kleen Cc: Andrew Morton , Andi Kleen , Mathieu Desnoyers , Ingo Molnar , linux-kernel@vger.kernel.org, Jason Baron , Rusty Russell , Adrian Bunk , Christoph Hellwig Subject: Re: [patch 02/12] Immediate Values - Architecture Independent Code Message-ID: <20090928223735.74267e3e@infradead.org> In-Reply-To: <20090928195444.GF1656@one.firstfloor.org> References: <20090924132626.485545323@polymtl.ca> <20090924133359.218934235@polymtl.ca> <20090924212013.d27226c4.akpm@linux-foundation.org> <20090928012337.GC1656@one.firstfloor.org> <20090928104617.9c4b868a.akpm@linux-foundation.org> <20090928200317.64a419ff@infradead.org> <20090928195444.GF1656@one.firstfloor.org> Organization: Intel X-Mailer: Claws Mail 3.7.2 (GTK+ 2.16.6; i586-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1084 Lines: 26 On Mon, 28 Sep 2009 21:54:45 +0200 Andi Kleen wrote: > > btw just to add to this: > > caches are unified code/data after L1 in general... it then does not > > matter much if you encode the "almost constant" in the codestream or > > slightly farther away, in both cases it takes up cache space. > > It does take up cache space, but when it's embedded in the instruction > stream the CPU has it usually already prefetched (CPUs are very good > at prefetching instructions). That's often not the case > with arbitary data accesses like this. this makes me wonder what happens when a variable is used in multiple places... that makes the icache overhead multiply right? -- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org -- 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/