From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kai Zimmer Subject: slow responsiveness of kvm guests Date: Fri, 31 Jul 2009 14:15:19 +0000 (GMT) Message-ID: <737790504.9407.1249049719234.JavaMail.mail@webmail05> Reply-To: kai@zimmer.net Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit To: kvm@vger.kernel.org Return-path: Received: from smtprelay0028.hostedemail.com ([216.40.44.28]:37017 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751458AbZGaOPU (ORCPT ); Fri, 31 Jul 2009 10:15:20 -0400 Received: from filter.hostedemail.com (ff-bigip1 [10.5.19.254]) by smtprelay02.hostedemail.com (Postfix) with SMTP id DDC3AFFAF2F for ; Fri, 31 Jul 2009 14:15:19 +0000 (UTC) Received: from webmail05 (imap-ext [216.40.42.5]) (Authenticated sender: kai@zimmer.net) by omf04.hostedemail.com (Postfix) with ESMTP for ; Fri, 31 Jul 2009 14:15:19 +0000 (UTC) Sender: kvm-owner@vger.kernel.org List-ID: Hi, i have three guests running via qemu-kvm. All three are webservers using apache2/django and mysql. System load is very low on all guests and the host, too. Guest 1 reaction times (web server, ssh) are fine as long as no other guest is getting busy. When i ssh to guest 2 it takes 5-15 seconds until i get a login. When i run top or htop on one of the guests the other guests don't react for 5 seconds (webservers or typing in ssh shell). My colleagues already try to convince me to use xen instead... already - disabled apm and acpi in the guests - turned Hyperthreading off - tried different i/o schedulers: cfq vs. deadline. Result is the same. - nailed down guest process via taskset to separate cpu cores host is OpenSuSe 11.1 x86_64 kvm-78-6.5.1 2xXeon 5550 Nehalem (Quadcores, Speedstep-enabled) 48 GB RAM 1 GB Ethernet as tap interface all three guests are Debian 5.0 x86_64 two virtual cpus 4GB RAM (hugepage-backed) started via qemu-kvm -hda xyz.qcow2 -daemonize -net nic,model=virtio -net tap -k de -m 3584 -smp 2 -mem-path /hugepages -vnc :2 Any ideas what goes wrong here? Kai