From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: KVM got slow after adding more physical memory to host Date: Tue, 06 Sep 2011 18:13:27 +0300 Message-ID: <4E663897.60901@redhat.com> References: <20110906140201.GF18218@pcnci.linuxbox.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Nikola Ciprich Return-path: Received: from mx1.redhat.com ([209.132.183.28]:6259 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754766Ab1IFPNu (ORCPT ); Tue, 6 Sep 2011 11:13:50 -0400 In-Reply-To: <20110906140201.GF18218@pcnci.linuxbox.cz> Sender: kvm-owner@vger.kernel.org List-ID: On 09/06/2011 05:02 PM, Nikola Ciprich wrote: > Hello, > > I'm trying to solve quite a weird problem on one of our customers' box. > It's quad core Xeon X3430 @ 2.40GHz, running 64bit centos with 2.6.38 (I also tried upgrading to > 2.6.39). > After increasing physical memory from 16 to 20GB, all guest got incredibly slow, starting just > one windows or linux guest causes host to be quite slow, and quest seems to be even slower. > hardware virtualisation is on, KVM is used, no relevant update since the update. > here's about 3 seconds of kvm_stat: > > kvm_exit 659513 103922 > kvm_entry 659505 103920 > kvm_emulate_insn 631118 99344 > kvm_exit(IO_INSTRUCTION) 625223 98398 > kvm_userspace_exit 624979 98359 > kvm_pio 624970 98357 How many guests in there? Please post a trace as per http://www.linux-kvm.org/page/Tracing. > but according to atop, there is almost no I/O activity from guests, and running top in them > shows them to really be idle... > but they eat like 60-70% of host CPU core time each.. > > Do You have any idea on what should I check? > thanks a lot in advance Please post /proc/mtrr and /proc/iomem. -- error compiling committee.c: too many arguments to function