From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754651AbXJaGLy (ORCPT ); Wed, 31 Oct 2007 02:11:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752851AbXJaGLq (ORCPT ); Wed, 31 Oct 2007 02:11:46 -0400 Received: from gatekeeper.ncic.ac.cn ([159.226.41.188]:63934 "HELO ac.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1752499AbXJaGLp convert rfc822-to-8bit (ORCPT ); Wed, 31 Oct 2007 02:11:45 -0400 Message-ID: <47281C75.4040106@sina.com.cn> Date: Wed, 31 Oct 2007 14:11:01 +0800 From: tgh User-Agent: Thunderbird 1.5.0.7 (Windows/20060909) MIME-Version: 1.0 To: Jeremy Fitzhardinge CC: Xen-devel , Jeremy Fitzhardinge , Andi Kleen , lkml , Chris Wright , Andrew Morton Subject: Re: [Xen-devel] [patch 30/44] xen: Add support for preemption References: <20070716231536.937393000@xensource.com>> <20070716232915.672717000@xensource.com>> <4726F51C.4030709@sina.com.cn> <4727690F.4030502@goop.org> <4727D926.6050004@sina.com.cn> <4727DC88.2020803@goop.org> In-Reply-To: <4727DC88.2020803@goop.org> Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Thank you for your reply and what about the kernel thread in the xen hypervisor,are there some instance of kernel threads running in the hypervisor? I am not sure ,but somewhere I read that there is no kernel thread in the xen hypervisor ,is it true or what about it? Thanks in advance Jeremy Fitzhardinge дµÀ: > tgh wrote: > >> Thank for your reply >> and I still have several questions >> >> >>> Yes, that's the normal mode of operation. The hypervisor will timeslice >>> multiple vcpus onto a single vcpu. >>> >>> >>> >> that is ,the VM could be preempted by xen,and could xen hypervisor also >> be preempted to reschedule other vm or xen kernel thread?and are there >> the counterpart abstractions in xen for kernel thread in linux? >> >> > > Yes, a vcpu in Xen is the same as a task in the kernel. In the same way > the kernel multiplexes multiple tasks onto your cpu(s), Xen multiplexes > multiple vcpus onto your cpu(s). This isn't directly visible to the > guest kernel, in the same way that user processes can't generally > observe timeslicing. > > >>> This patch doesn't relate to that; it's whether a Xen Linux guest's >>> kernel can be preempted to reschedule processes while running under Xen. >>> >>> >>> >> that is ,the patch makes the guest's kernel, rather than xen, be able to >> be preempted ,is it right? >> >> > > Yes. Previous to that change, kernel preemption was disabled when > compiling Xen support in. > > J > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel > > >