From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52464) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d3P9o-0007aA-Pm for qemu-devel@nongnu.org; Wed, 26 Apr 2017 11:47:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d3P9j-0006E4-UU for qemu-devel@nongnu.org; Wed, 26 Apr 2017 11:47:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56459) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1d3P9j-0006Dk-OA for qemu-devel@nongnu.org; Wed, 26 Apr 2017 11:47:03 -0400 References: <830bfc39-56c7-a901-9ebb-77d6e7a5614c@huawei.com> <874lxeovrg.fsf@secure.mitica> <7cd332ec-48d4-1feb-12e2-97b50b04e028@huawei.com> <20170424164244.GJ2362@work-vm> From: Paolo Bonzini Message-ID: Date: Wed, 26 Apr 2017 17:46:56 +0200 MIME-Version: 1.0 In-Reply-To: <20170424164244.GJ2362@work-vm> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] About QEMU BQL and dirty log switch in Migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" , Yang Hongyang Cc: quintela@redhat.com, "qemu-devel@nongnu.org" , Huangzhichao , wangxinxin.wang@huawei.com, "Gonglei (Arei)" On 24/04/2017 18:42, Dr. David Alan Gilbert wrote: > I suppose there's a few questions; > a) Do we actually need the BQL - and if so why > b) What actually takes 13s? It's probably worth figuring > out where it goes, the whole bitmap is only 1GB isn't it > even on a 4TB machine, and even the simplest way to fill > that takes way less than 13s. It's more likely that it is the migration_bitmap_sync immediately after that. I think it is possible to move migration_bitmap_sync outside BQL. It should be simpler to evaluate that after Juan's cleanups go in. Paolo