From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: QEMU PIC indirection patch for in-kernel APIC work Date: Wed, 04 Apr 2007 19:58:34 +0300 Message-ID: <4613D93A.5020902@qumranet.com> References: <8FFF7E42E93CC646B632AB40643802A8025B96AA@scsmsx412.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: "Nakajima, Jun" Return-path: In-Reply-To: <8FFF7E42E93CC646B632AB40643802A8025B96AA-1a9uaKK1+wJcIJlls4ac1rfspsVTdybXVpNB7YpNyf8@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Nakajima, Jun wrote: > I compared the performance on Xen and KVM for kernel build using the > same guest image. Looks like KVM was (kvm-17) three times slower as far > as we tested, and that high load of qemu was one of the symptoms. We are > looking at the shadow code, but the load of qemu looks very high. I > remember we had similar problems in Xen before, but those were fixed. > Someone should take a look at the qemu side. > I'd expect the following issues to dominate: - the shadow cache is quite small at 256 pages. Increasing it may increase performance. - we haven't yet taught the scheduler that migrating vcpus is expensive due to the IPI needed to fetch the vmcs. Maybe running with 'taskset 1' would help - shadow eviction policy is FIFO, not LRU, which probably causes many page faults. Running kvm_stat can help show what's going on. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV