From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Lieven Subject: Re: [Qemu-devel] Stalls on Live Migration of VMs with a lot of memory Date: Wed, 04 Jan 2012 11:53:21 +0100 Message-ID: <4F042FA1.5090909@dlh.net> References: <032f49425e7284e9f050064cd30855bb@mail.dlh.net> <4F03AD98.7020700@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org To: Shu Ming Return-path: Received: from ssl.dlh.net ([91.198.192.8]:42302 "EHLO ssl.dlh.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754078Ab2ADKxX (ORCPT ); Wed, 4 Jan 2012 05:53:23 -0500 In-Reply-To: <4F03AD98.7020700@linux.vnet.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: On 04.01.2012 02:38, Shu Ming wrote: > On 2012-1-4 2:04, Peter Lieven wrote: >> Hi all, >> >> is there any known issue when migrating VMs with a lot of (e.g. 32GB) >> of memory. >> It seems that there is some portion in the migration code which takes >> too much time when the number >> of memory pages is large. >> >> Symptoms are: Irresponsive VNC connection, VM stalls and also >> irresponsive QEMU Monitor (via TCP). >> >> The problem seems to be worse on 10G connections between 2 Nodes (i >> already tried limiting the >> bandwidth with the migrate_set_speed command) than on 1G connections. > Is the migration accomplished finally? How long will that be? I did > a test on VM with 4G and it took me about two seconds. it seems that the majority of time (90%) is lost in: cpu_physical_memory_reset_dirty(current_addr, current_addr + TARGET_PAGE_SIZE, MIGRATION_DIRTY_FLAG); anyone any idea, to improve this?