From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH 0/8] KVM updates for 2.6.20-rc2 Date: Thu, 28 Dec 2006 15:07:42 +0100 Message-ID: <20061228140742.GA10033@elte.hu> References: <45939755.7010603@qumranet.com> <20061228103345.GA4708@elte.hu> <4593A4B7.2070404@qumranet.com> <20061228113038.GA16190@elte.hu> <4593B948.5090009@qumranet.com> <20061228133746.GC3392@elte.hu> <4593CB61.5050709@qumranet.com> <20061228135020.GA7606@elte.hu> <4593CD74.6060202@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel Return-path: To: Avi Kivity Content-Disposition: inline In-Reply-To: <4593CD74.6060202-atKUWr5tajBWk0Htik3J/w@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 * Avi Kivity wrote: > >yeah. Would be nice to see some hard numbers about how many cycles all > >these context load/save variants take. > > PIO latency on AMD (including a trip to qemu and back) is 5500 cycles > [1]. Intel is significantly higher. > > [1] http://virt.kernelnewbies.org/KVM/Performance ok. We need the IPI only on VMX, right? That's because it has cached VM state in the CPU that needs to be flushed out to the public VM area before it can be loaded into another CPU, correct? Is there no cheap way to do this flushing preemptively (say in vcpu_put()), to make the VM context potentially loadable into another CPU? Ingo ------------------------------------------------------------------------- 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