From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:52825)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <mrhines@linux.vnet.ibm.com>) id 1XRtdm-0003Xb-9n
	for qemu-devel@nongnu.org; Wed, 10 Sep 2014 21:57:51 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <mrhines@linux.vnet.ibm.com>) id 1XRtdd-0003La-8U
	for qemu-devel@nongnu.org; Wed, 10 Sep 2014 21:57:42 -0400
Received: from e34.co.us.ibm.com ([32.97.110.152]:43756)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <mrhines@linux.vnet.ibm.com>) id 1XRtdd-0003LW-0V
	for qemu-devel@nongnu.org; Wed, 10 Sep 2014 21:57:33 -0400
Received: from /spool/local
	by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only!
	Violators will be prosecuted
	for <qemu-devel@nongnu.org> from <mrhines@linux.vnet.ibm.com>;
	Wed, 10 Sep 2014 19:57:32 -0600
Received: from b03cxnp07029.gho.boulder.ibm.com
	(b03cxnp07029.gho.boulder.ibm.com [9.17.130.16])
	by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 4703F19D803E
	for <qemu-devel@nongnu.org>; Wed, 10 Sep 2014 19:57:17 -0600 (MDT)
Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170])
	by b03cxnp07029.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with
	ESMTP id s8ANrRvO7733566
	for <qemu-devel@nongnu.org>; Thu, 11 Sep 2014 01:53:27 +0200
Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1])
	by d03av04.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP
	id s8B1vTPq006817
	for <qemu-devel@nongnu.org>; Wed, 10 Sep 2014 19:57:30 -0600
Message-ID: <54110187.7060107@linux.vnet.ibm.com>
Date: Thu, 11 Sep 2014 09:57:27 +0800
From: "Michael R. Hines" <mrhines@linux.vnet.ibm.com>
MIME-Version: 1.0
References: <e8665241-6327-45ee-8762-f423cdcb7169@mailpro>
	<54101328.4070802@huawei.com>
In-Reply-To: <54101328.4070802@huawei.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] ballooning not working on hotplugged  pc-dimm
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: zhanghailiang <zhang.zhanghailiang@huawei.com>, Alexandre DERUMIER <aderumier@odiso.com>
Cc: hinesmr@cn.ibm.com, qemu-devel <qemu-devel@nongnu.org>

On 09/10/2014 05:00 PM, zhanghailiang wrote:
> On 2014/9/9 11:05, Alexandre DERUMIER wrote:
>> Hello,
>>
>> I was playing with pc-dimm hotplug, and I notice that balloning is 
>> not working on
>> memory space of pc-dimm devices.
>>
>> example:
>>
>> qemu -m size=1024,slots=255,maxmem=15000M
>>
>> #free -m : 1024M
>> ->  qmp balloon 512M
>> #free -m : 512M
>>
>> ->  hotplug pc-dimm 1G:
>>
>> #free -m : 1512M
>>
>>
>> (This is the same behavior if qemu is started with pc-dimm devices)
>>
>>
>> qemu 2.1
>> Guest kernel : 3.12.
>>
>>
>>
>> Does it need a guest balloon module update ?
>>
>> Regards,
>>
>> Alexandre Derumier
>>
>>
>>
> Hi,
>
> I noticed this fault also;-), this is a bug in qemu, And some work in 
> process...
>
> Actually in QEMU the hotplugged memory(named hotplug-memory) is 
> distinguished
> from the common memory(named pc.ram). When do balloon action, QEMU 
> wrongly
> stats the ram_size.
>
> I will send a patch series which also include other bug fix for the 
> memory hotplug.
>
> Thanks,
> zhanghailiang
>
>
>

Why does hotplugging use a different name?

This also affects RDMA live migration - we are explicitly looking up 
"pc.ram" ram blocks and pinning them for memory registration with Linux.

- Michael