From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Gross Subject: Re: [Patch 2 of 2]: PV-domain SMP performance Linux-part Date: Fri, 19 Dec 2008 11:48:20 +0100 Message-ID: <494B7BF4.70304@fujitsu-siemens.com> References: <494B5769.6030206@fujitsu-siemens.com> <494B7892.76E4.0078.0@novell.com> <494B721D.6000003@fujitsu-siemens.com> <494B8722.76E4.0078.0@novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <494B8722.76E4.0078.0@novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jan Beulich Cc: "xen-devel@lists.xensource.com" , Keir Fraser List-Id: xen-devel@lists.xenproject.org Jan Beulich wrote: >>>> Juergen Gross 19.12.08 11:06 >>> >> Regarding handling this in Xen only: not to deschedule a vcpu in case of >> interrupts disabled is easy, but how would you deschedule it after interrupts >> are allowed again? > > It's all the same as with the newly added flag of yours - it requires cooperation > from the guest (plus the forced de-schedule if it fails to do so). It's just that > you don't need to set two flags when disabling interrupts, that second flag > would only be needed when you want to avoid being de-scheduled for > reasons other than event delivery being disabled. Just another thought: My approach was more compatible. Only a guest which is aware of the new flag will set it and in turn respect the request of the hypervisor to give up control after enabling de-scheduling again. Old guests would always be regarded as non-cooperative. Juergen -- Juergen Gross Principal Developer IP SW OS6 Telephone: +49 (0) 89 636 47950 Fujitsu Siemens Computers e-mail: juergen.gross@fujitsu-siemens.com Otto-Hahn-Ring 6 Internet: www.fujitsu-siemens.com D-81739 Muenchen Company details: www.fujitsu-siemens.com/imprint.html