From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752163Ab1GYOOk (ORCPT ); Mon, 25 Jul 2011 10:14:40 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:44668 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752102Ab1GYOOh (ORCPT ); Mon, 25 Jul 2011 10:14:37 -0400 Date: Mon, 25 Jul 2011 16:13:39 +0200 From: Ingo Molnar To: Andrew Lutomirski Cc: x86 , linux-kernel@vger.kernel.org, Linus Torvalds , Arjan van de Ven , Avi Kivity Subject: Re: [PATCH 3.1?] x86: Remove useless stts/clts pair in __switch_to Message-ID: <20110725141339.GC3297@elte.hu> References: <38f1d91a44c243a91e441a947fed4b076dcd4ca1.1311587947.git.luto@mit.edu> <20110725111224.GP28787@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andrew Lutomirski wrote: > > Also, if you are tempted by the prospect of possibly enabling > > vector instructions for the x86 kernel, we could try that too, > > and get multiple speedups for the price of having to debug the > > tree only once ;-) > > I'll play with it. I have some other cleanup / speedup ideas, too, > and I'll see where they go. Given that the kernel doesn't really > use floating-point math, I'm not sure that gcc will do much unless > we turn on -ftree-vectorize, and that's a little scary. It's indeed scary - but as long as it boots it would allow some baseline figures to be estimated - is there any win, and if yes, how much. It might be a complete dud in the end. Thanks, Ingo