From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 00/13] KVM: MMU: fast page fault Date: Wed, 11 Apr 2012 12:15:08 +0300 Message-ID: <4F854B9C.3000405@redhat.com> References: <4F742951.7080003@linux.vnet.ibm.com> <4F82E04E.6000900@redhat.com> <20120409175829.GB21894@amt.cnet> <4F8329D3.7000605@gmail.com> <20120409194614.GB23053@amt.cnet> <4F84059D.80606@redhat.com> <20120411014712.GA15327@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Xiao Guangrong , Xiao Guangrong , LKML , KVM To: Marcelo Tosatti Return-path: In-Reply-To: <20120411014712.GA15327@amt.cnet> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 04/11/2012 04:47 AM, Marcelo Tosatti wrote: > On Tue, Apr 10, 2012 at 01:04:13PM +0300, Avi Kivity wrote: > > On 04/09/2012 10:46 PM, Marcelo Tosatti wrote: > > > Perhaps the mmu_lock hold times by get_dirty are a large component here? > > > > That's my concern, because it affects the scaling of migration for wider > > guests. > > > > > If that can be alleviated, not only RO->RW faults benefit. > > > > Those are the most common types of faults on modern hardware, no? > > Depends on your workload, of course. If there is memory pressure, > 0->PRESENT might be very frequent. My point is that reduction of > mmu_lock contention is a good thing overall. > Agreed. -- error compiling committee.c: too many arguments to function