From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932287AbXBPK4K (ORCPT ); Fri, 16 Feb 2007 05:56:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964781AbXBPK4K (ORCPT ); Fri, 16 Feb 2007 05:56:10 -0500 Received: from smtp.osdl.org ([65.172.181.24]:40462 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932287AbXBPK4I (ORCPT ); Fri, 16 Feb 2007 05:56:08 -0500 Date: Fri, 16 Feb 2007 02:54:52 -0800 From: Andrew Morton To: Keir Fraser Cc: Christian Limpach , Jeremy Fitzhardinge , Chris Wright , Andi Kleen , , Ian Pratt , , Steven Hand , Subject: Re: [patch 14/21] Xen-paravirt: Add XEN config options and disableunsupported config options. Message-Id: <20070216025452.d25e3545.akpm@linux-foundation.org> In-Reply-To: References: <20070216020947.03e1726e.akpm@linux-foundation.org> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-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 On Fri, 16 Feb 2007 10:47:11 +0000 Keir Fraser wrote: > On 16/2/07 10:09, "Andrew Morton" wrote: > > > Are the places where the domU code references machine addresses splattered > > all over the code? If not, they can just be wrapped with > > preempt_disable/preempt_enable? > > The main places where machine addresses are 'visible' are any code that > holds a pte_t,pmd_t,pud_t,pgd_t. We hide the machine-to-pseudophysical and > pseudophysical-to-machine translations inside e.g., pte_val() and __pte() > (i.e., constructors and extractors for page table entries). Obviously the > users of these macros are open coded all over the place, quite apart from > the performance cost of sprinkling preempt_{enable,disable} so liberally. OK, you're screwed. I agree that the process freezer is the way out of that one. Ingo said that he's clocked the freezer at a few milliseconds. But if it's any higher than that it'll need to get sped up once we convert cpu hotplug to use it. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [patch 14/21] Xen-paravirt: Add XEN config options and disableunsupported config options. Date: Fri, 16 Feb 2007 02:54:52 -0800 Message-ID: <20070216025452.d25e3545.akpm@linux-foundation.org> References: <20070216020947.03e1726e.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.osdl.org Errors-To: virtualization-bounces@lists.osdl.org To: Keir Fraser Cc: Chris Wright , Andi Kleen , xen-devel@lists.xensource.com, Ian Pratt , virtualization@lists.osdl.org, Steven Hand , Christian Limpach , linux-kernel@vger.kernel.org List-Id: virtualization@lists.linuxfoundation.org On Fri, 16 Feb 2007 10:47:11 +0000 Keir Fraser wrote: > On 16/2/07 10:09, "Andrew Morton" wrote: > = > > Are the places where the domU code references machine addresses splatte= red > > all over the code? If not, they can just be wrapped with > > preempt_disable/preempt_enable? > = > The main places where machine addresses are 'visible' are any code that > holds a pte_t,pmd_t,pud_t,pgd_t. We hide the machine-to-pseudophysical and > pseudophysical-to-machine translations inside e.g., pte_val() and __pte() > (i.e., constructors and extractors for page table entries). Obviously the > users of these macros are open coded all over the place, quite apart from > the performance cost of sprinkling preempt_{enable,disable} so liberally. OK, you're screwed. I agree that the process freezer is the way out of tha= t one. Ingo said that he's clocked the freezer at a few milliseconds. But if it's any higher than that it'll need to get sped up once we convert cpu hotplug to use it.