From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752848Ab1IFSvG (ORCPT ); Tue, 6 Sep 2011 14:51:06 -0400 Received: from claw.goop.org ([74.207.240.146]:50819 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751670Ab1IFSvD (ORCPT ); Tue, 6 Sep 2011 14:51:03 -0400 Message-ID: <4E666B92.9010300@goop.org> Date: Tue, 06 Sep 2011 11:50:58 -0700 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:6.0) Gecko/20110816 Thunderbird/6.0 MIME-Version: 1.0 To: Don Zickus CC: Peter Zijlstra , "H. Peter Anvin" , Linus Torvalds , Ingo Molnar , the arch/x86 maintainers , Linux Kernel Mailing List , Nick Piggin , Avi Kivity , Marcelo Tosatti , KVM , Andi Kleen , Xen Devel , Jeremy Fitzhardinge , Stefano Stabellini Subject: Re: [PATCH 08/13] xen/pvticketlock: disable interrupts while blocking References: <38bb37e15f6e5056d5238adac945bc1837a996ec.1314922370.git.jeremy.fitzhardinge@citrix.com> <1314974826.1861.1.camel@twins> <4E612EA1.20007@goop.org> <1314996468.8255.0.camel@twins> <4E614FBD.2030509@goop.org> <20110906151408.GA7459@redhat.com> <4E66615E.8070806@goop.org> <20110906182758.GR5795@redhat.com> In-Reply-To: <20110906182758.GR5795@redhat.com> X-Enigmail-Version: 1.3.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/06/2011 11:27 AM, Don Zickus wrote: >> But on the other hand, I don't really care if you can say that this path >> will never be called in a virtual machine. > Does virtual machines support hot remove of cpus? Probably not > considering bare-metal barely supports it. The only reason you'd want to is to add/remove VCPUs as a mechanism of resource control, so if you were removing a VCPU it wouldn't matter much which one you choose. In other words, there's no reason you'd ever need to remove the BSP in favour of one of the other CPUs. Anyway, I'm not going to lose any sleep over this issue. J From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [PATCH 08/13] xen/pvticketlock: disable interrupts while blocking Date: Tue, 06 Sep 2011 11:50:58 -0700 Message-ID: <4E666B92.9010300@goop.org> References: <38bb37e15f6e5056d5238adac945bc1837a996ec.1314922370.git.jeremy.fitzhardinge@citrix.com> <1314974826.1861.1.camel@twins> <4E612EA1.20007@goop.org> <1314996468.8255.0.camel@twins> <4E614FBD.2030509@goop.org> <20110906151408.GA7459@redhat.com> <4E66615E.8070806@goop.org> <20110906182758.GR5795@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , Nick Piggin , KVM , Stefano Stabellini , Peter Zijlstra , the arch/x86 maintainers , Linux Kernel Mailing List , Andi Kleen , Avi Kivity , Jeremy Fitzhardinge , "H. Peter Anvin" , Ingo Molnar , Linus Torvalds , Xen Devel To: Don Zickus Return-path: In-Reply-To: <20110906182758.GR5795@redhat.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com List-Id: kvm.vger.kernel.org On 09/06/2011 11:27 AM, Don Zickus wrote: >> But on the other hand, I don't really care if you can say that this path >> will never be called in a virtual machine. > Does virtual machines support hot remove of cpus? Probably not > considering bare-metal barely supports it. The only reason you'd want to is to add/remove VCPUs as a mechanism of resource control, so if you were removing a VCPU it wouldn't matter much which one you choose. In other words, there's no reason you'd ever need to remove the BSP in favour of one of the other CPUs. Anyway, I'm not going to lose any sleep over this issue. J