Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965301AbXAHJrm (ORCPT ); Mon, 8 Jan 2007 04:47:42 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965302AbXAHJrm (ORCPT ); Mon, 8 Jan 2007 04:47:42 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:37803 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965301AbXAHJrh (ORCPT ); Mon, 8 Jan 2007 04:47:37 -0500 Date: Mon, 8 Jan 2007 10:43:59 +0100 From: Ingo Molnar To: Avi Kivity Cc: kvm-devel , linux-kernel@vger.kernel.org Subject: Re: [announce] [patch] KVM paravirtualization for Linux Message-ID: <20070108094359.GB30482@elte.hu> References: <20070105215223.GA5361@elte.hu> <45A0E586.50806@qumranet.com> <20070107174416.GA14607@elte.hu> <45A1FF4E.1020106@qumranet.com> <20070108083935.GB18259@elte.hu> <45A20A0A.70403@qumranet.com> <20070108091819.GB26587@elte.hu> <45A20F60.20207@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45A20F60.20207@qumranet.com> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -5.9 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-5.9 required=5.9 tests=ALL_TRUSTED,BAYES_00 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts -2.6 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 851 Lines: 20 * Avi Kivity wrote: > Looks like a lot of complexity for very little gain. I'm not sure > what the vmwrite cost is, cut it can't be that high compared to > vmexit. while i disagree with characterising one extra parameter passed down plus one extra branch as 'a lot of complexity', i agree that making the flush a NOP on VMX is even better. (if it's possible without breaking future hardware) I guess you are right that the only true cost here is the vmwrite cost, and that there's no impact on CR3 flushing (because it happens unconditionally). Forget about this patch. Ingo - 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/