From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: faster boot with -no-kvm? Date: Thu, 12 Apr 2007 17:35:19 +0300 Message-ID: <461E43A7.8050307@qumranet.com> References: <87veg1ybb0.fsf@grogan.peloton> <461E3AA5.10408@qumranet.com> <87ejmpy8fb.fsf@grogan.peloton> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: David Abrahams Return-path: In-Reply-To: <87ejmpy8fb.fsf-2bi8v6C3s58ZC2cDDG0gXw@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 David Abrahams wrote: > on Thu Apr 12 2007, Avi Kivity wrote: > > >> David Abrahams wrote: >> >>> When I start my Windows VM with -no-kvm, it seems to boot much more >>> quickly than without. >>> >> You probably have acpi enabled in Windows. This causes massive >> slowdowns in kvm; the real fix will unfortunately require you to upgrade >> your hardware. >> > > My physical hardware? Which part? > The part that currently doesn't virtualize the apic tpr: the cpu. It happens that Windows in acpi mode likes to bang on this register quite a lot, and that the penalty for accessing this register is several microseconds (instead of nanoseconds). Most of the time in a (virtual) Windows boot is spent on reading and writing this register. > Is starting the vm with -no-acpi insufficient? I just realized, I > haven't been doing that. > It won't help if Windows wants acpi, I think. -- 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