Re: [Xen-devel] S3 sleep in dom0 breaks dom0<->domU wallclock s

To:	Jan Beulich <JBeulich@xxxxxxxxxx>
Subject:	Re: [Xen-devel] S3 sleep in dom0 breaks dom0<->domU wallclock synchronization
From:	Joanna Rutkowska <joanna@xxxxxxxxxxxxxxxxxxxxxx>
Date:	Tue, 06 Jul 2010 12:27:39 +0200
Cc:	Jeremy Fitzhardinge <jeremy@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, Jeremy Fitzhardinge <Jeremy.Fitzhardinge@xxxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>, Rafal Wojtczuk <rafal@xxxxxxxxxxxxxxxxxxxxxx>
Delivery-date:	Tue, 06 Jul 2010 03:29:07 -0700
Dkim-signature:	v=1; a=rsa-sha1; c=relaxed/relaxed; d=messagingengine.com; h=message-id:date:from:mime-version:to:cc:subject:references:in-reply-to:content-type; s=smtpout; bh=wUJN8tJJzE1MnkSeUYu+M1F6bDQ=; b=H3AeTui0vxrKQMbyFDu/8V3qDvd/rYziVJ3SIHZobOLTatKRqm7bJDeGLRJn/NMHWZQsp1J/D8V30q1LVOGgMHD943RNpwaQS64nJhA/2JVBZL0V0swlwNSjVoMtChjSyyamPEdl09HVSvedGdgXUy0XigyzaQKCazpyOkbxAvc=
Envelope-to:	www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to:	<4C331B600200007800009B4F@xxxxxxxxxxxxxxxxxx>
List-help:	<mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id:	Xen developer discussion <xen-devel.lists.xensource.com>
List-post:	<mailto:xen-devel@lists.xensource.com>
List-subscribe:	<http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe:	<http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References:	<C858671D.19765%keir.fraser@xxxxxxxxxxxxx> <4C32F320.3060103@xxxxxxxxxxxxxxxxxxxxxx> <4C331B600200007800009B4F@xxxxxxxxxxxxxxxxxx>
Sender:	xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent:	Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.10) Gecko/20100621 Fedora/3.0.5-1.fc13 Lightning/1.0b2pre Thunderbird/3.0.5

On 07/06/10 12:02, Jan Beulich wrote:
>>>> On 06.07.10 at 11:10, Joanna Rutkowska <joanna@xxxxxxxxxxxxxxxxxxxxxx> 
>>>> wrote:
>> On 07/06/10 05:52, Keir Fraser wrote:
>>> On 05/07/2010 23:50, "Jeremy Fitzhardinge" <jeremy@xxxxxxxx> wrote:
>>>
>>>>> BTW: wouldn't it be good to actually notify them? Consider e.g. DomU
>>>>> that has some device assigned to it (say a NIC) -- if we emulated S3
>>>>> suspend/resume for this DomU, there is a hope it would properly
>>>>> suspend/reinitialize the NIC, wouldn't it?
>>>>>   
>>>>
>>>> I guess?  That implies some kind of PV S3 suspend and resume event to
>>>> feed into the dom U's device model.  What does 2.6.18-xen do?
>>>
>>> I don't think our S3 support is very compatible with PV device passthrough.
>>> We support HVM virtual S3, and can S3-sleep HVM guests across real host S3,
>>> but we don't have similar for PV guests.
>>>
>>
>> How about implementing something very simple, like a notification via
>> xenstore (say, Dom0 would be setting some key)? Interested DomUs could
>> then register a watch, and get notified when the system was resumed from
>> S3. This would let them e.g. to call whatever hypercall is used normally
>> on DomU boot to sync DomU wallclock, or reinitialize/reconnect the NIC.
> 
> Wouldn't it be much simpler to not introduce any new logic at all and
> just let Dom0 tools/scripts take care of properly suspending
> (checkpointing) all (minimally all pv, but I would really think treating
> different kinds of guests differently here is unnecessary) guests
> before doing a host suspend, as Jeremy had suggested in an earlier
> reply?
> 

But wouldn't this require dumping all the VMs memory do disk? Can we use
xm pause instead, i.e. will it notify VMs properly?

j.

signature.asc
Description: OpenPGP digital signature

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

WARNING - OLD ARCHIVES

xen-devel

Re: [Xen-devel] S3 sleep in dom0 breaks dom0<->domU wallclock synchroni