From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anders Subject: Re: KVM power usage - high wakeup rates Date: Sun, 22 Jun 2008 15:55:15 +0200 Message-ID: <485E59C3.1020607@flac.kalibalik.dk> References: <485AA6A7.2060806@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit To: kvm@vger.kernel.org Return-path: Received: from 77.75.163.100.customers.telelet.dk ([77.75.163.100]:37586 "EHLO smtp.hotelhot.dk" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1756594AbYFVOWn (ORCPT ); Sun, 22 Jun 2008 10:22:43 -0400 Received: from smtp.hotelhot.dk (localhost [127.0.0.1]) by smtp.hotelhot.dk (Postfix) with ESMTP id 1CB6014062 for ; Sun, 22 Jun 2008 15:55:20 +0200 (CEST) Received: from [192.168.0.201] (router.kalibalik.dk [192.168.0.1]) by smtp.hotelhot.dk (Postfix) with ESMTP id AA8991405A for ; Sun, 22 Jun 2008 15:55:19 +0200 (CEST) In-Reply-To: <485AA6A7.2060806@codemonkey.ws> Sender: kvm-owner@vger.kernel.org List-ID: Anthony Liguori wrote: > With the default options, my idle winxp guest causes about 550 > wakeups/sec which is pretty close to what I'd expect. I don't think > you'll get much better than that without using a dynticks guest. According to powertop, I had about 15 kvm wakeups/sec with my previous setup (nohz, no display). Now I upgraded to kvm-70 and the timer interrupt has reappeared so I have this: Top causes for wakeups: 25,4% (112,4) : function call interrupts 22,6% (100,0) qemu-system-x86 : kvm_arch_vcpu_ioctl_run (pit_timer_fn) 22,6% (100,0) qemu-system-x86 : __kvm_migrate_timers (apic_timer_fn) 8,7% ( 38,5) qemu-system-x86 : sys_timer_settime (posix_timer_fn) What could be the cause for this change? The previous kvm was from Ubuntu 8.04, there are no changes in the guest. In general, what are the best host/guest settings for a low number of wakeups? Thanks, Anders.