From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: Re: [PATCH] kvm: fix slot flags sync between Qemu and KVM Date: Wed, 08 Apr 2015 14:37:41 +0800 Message-ID: <5524CCB5.7080102@linux.intel.com> References: <5524CC0E.8020208@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm@vger.kernel.org, "qemu-devel@nongnu.org" , "Li, Wanpeng" To: Paolo Bonzini Return-path: Received: from mga11.intel.com ([192.55.52.93]:39026 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751163AbbDHGkM (ORCPT ); Wed, 8 Apr 2015 02:40:12 -0400 In-Reply-To: <5524CC0E.8020208@linux.intel.com> Sender: kvm-owner@vger.kernel.org List-ID: On 04/08/2015 02:34 PM, Xiao Guangrong wrote: > We noticed that KVM keeps tracking dirty for the memslots when > live migration failed which causes bad performance due to huge > page mapping disallowed for this kind of memslot > > It is caused by slot flags does not properly sync-ed between Qemu > and KVM. Current code doing slot update depends on slot->flags > which hopes to omit unnecessary ioctl. However, slot->flags only > reflects the stauts of corresponding memory region, vmsave and > live migration do dirty tracking which overset > KVM_MEM_LOG_DIRTY_PAGES for the slot. That causes the slot status > recorded in the flags does not exactly match the stauts in kernel. > > We fixed it by introducing slot->is_dirty_logging which indicates > the dirty status in kernel so that it helps us to sync the status > between userspace and kernel > > Wanpeng Li Sorry for the typo :( , this should be: Reported-by: Wanpeng Li