From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH v4 2/2] KVM: VMX: Add Posted Interrupt supporting Date: Mon, 25 Feb 2013 13:07:02 +0200 Message-ID: <20130225110702.GA12726@redhat.com> References: <20130223153144.GB25155@redhat.com> <20130223170513.GB8236@amt.cnet> <20130223194214.GD25155@redhat.com> <20130224141917.GC4284@redhat.com> <20130224180857.GA10477@amt.cnet> <20130225110159.GA12299@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Marcelo Tosatti , "kvm@vger.kernel.org" , "Zhang, Xiantao" To: "Zhang, Yang Z" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47496 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751412Ab3BYLHG (ORCPT ); Mon, 25 Feb 2013 06:07:06 -0500 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Mon, Feb 25, 2013 at 11:04:25AM +0000, Zhang, Yang Z wrote: > Gleb Natapov wrote on 2013-02-25: > > On Mon, Feb 25, 2013 at 08:42:52AM +0000, Zhang, Yang Z wrote: > >> Avi Kivity wrote on 2013-02-25: > >>> I didn't really follow, but is the root cause the need to keep track > >>> of interrupt coalescing? If so we can recommend that users use > >>> KVM_IRQ_LINE when coalescing is unneeded, and move interrupt injection > >>> with irq coalescing support to vcpu context. > >> So we can hide the capability KVM_CAP_IRQ_INJECT_STATUS when posted > > interrupt is enabled to force users doesn't to use KVM_IRQ_LINE_STATUS. Does > > this acceptable? > >> > >> The only case in KVM that need to know the interrupt injection status is vlapic > > timer. But since vlapic timer and vcpu are always in same pcpu, so there is no > > problem. > >> > > Not really. The primary user of this interface is RTC interrupt > > re-injection for Windows guests. > So without KVM_IRQ_LINE_STATUS capability, RTC cannot work well? > Windows guests may experience timedrift under CPU overcommit scenario. -- Gleb.