From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:57204) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UD37A-0008H4-VJ for qemu-devel@nongnu.org; Tue, 05 Mar 2013 20:25:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UD379-0004kO-HS for qemu-devel@nongnu.org; Tue, 05 Mar 2013 20:25:52 -0500 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:47301) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UD378-0004ju-Po for qemu-devel@nongnu.org; Tue, 05 Mar 2013 20:25:51 -0500 Received: from /spool/local by e28smtp08.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 6 Mar 2013 06:51:49 +0530 Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id 7F548E0053 for ; Wed, 6 Mar 2013 06:56:57 +0530 (IST) Received: from d28av02.in.ibm.com (d28av02.in.ibm.com [9.184.220.64]) by d28relay04.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r261Pd5531719516 for ; Wed, 6 Mar 2013 06:55:41 +0530 Received: from d28av02.in.ibm.com (loopback [127.0.0.1]) by d28av02.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r261Pgjb008045 for ; Wed, 6 Mar 2013 12:25:42 +1100 Message-ID: <51369AED.7020903@linux.vnet.ibm.com> Date: Wed, 06 Mar 2013 09:25:01 +0800 From: Wenchao Xia MIME-Version: 1.0 References: <1362038985-19008-1-git-send-email-xiawenc@linux.vnet.ibm.com> <20130228105035.GE2429@dhcp-200-207.str.redhat.com> <513013F0.2030007@linux.vnet.ibm.com> <5134B7F0.5020008@linux.vnet.ibm.com> <5135DF34.8060508@redhat.com> In-Reply-To: <5135DF34.8060508@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [RFC PATCH 0/4] savevm: save vmsate with fixed size List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Pavel Hrdina Cc: Kevin Wolf , aliguori@us.ibm.com, quintela@redhat.com, stefanha@gmail.com, qemu-devel@nongnu.org, pbonzini@redhat.com 于 2013-3-5 20:04, Pavel Hrdina 写道: > On 03/04/2013 04:04 PM, Wenchao Xia wrote: >> >>>> You probably get some improvements of the file size when the migration >>>> takes a while, depending on how much of the memory actually has to be >>>> saved. You might however end up with a lot more small writes instead of >>>> some big ones before, which might hurt performance. >>>> >>>> Do you have any data about the resulting performance and file size? >>>> >>> ah, an important issue I haven't test, thanks for tipping it, let >>> me add code for migration to file, and have a test. It also >>> can be optimized a bit in qemu_fseek(), but IMHO the optimization >>> for small writes would better goto block layer either in qemu >>> or underling components in system. >>> >> Hi,Juan >> talking about performance, in migration there are two buffer used, >> one in qemu_file as static array, and one in migration as dynamic >> allocated buffer, >> should they be merged to avoid extra memcpy? >> > > Hi Wenchao, > > This is already posted on qemu-devel list, > > http://lists.gnu.org/archive/html/qemu-devel/2013-02/msg04119.html > http://lists.gnu.org/archive/html/qemu-devel/2013-02/msg04222.html > > Pavel > Great, hope this can be upstream fast, thanks for tipping it. -- Best Regards Wenchao Xia