From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [PATCH] x86: extend runstate area updates Date: Fri, 02 Oct 2009 16:53:13 -0700 Message-ID: <4AC69269.3050806@goop.org> References: <4A8ABF4B020000780001049A@vpn.id2.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4A8ABF4B020000780001049A@vpn.id2.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 List-Id: xen-devel@lists.xenproject.org On 08/18/09 05:48, Jan Beulich wrote: > In order to give guests a hint at whether their vCPU-s are currently > scheduled (so they can e.g. adapt their behavior in spin loops), update > the run state area (if registered) also when de-scheduling a vCPU. > > Also fix an oversight in the compat mode implementation of > VCPUOP_register_runstate_memory_area. > > Please also consider for the 3.4 and 3.3 branches. > BTW, this actually changes the documented behaviour of register_runstate_memory_area: * 2. Only one shared area may be registered per VCPU. The shared area is * updated by the hypervisor each time the VCPU is scheduled. Thus * runstate.state will always be RUNSTATE_running and * runstate.state_entry_time will indicate the system time at which the * VCPU was last scheduled to run. not that I think anything was relying on the old behaviour (indeed, it's pretty unexpected behaviour). J