WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] Design question for PV superpage support

To: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>, Dave McCracken <dcm@xxxxxxxx>, "Mick.Jordan@xxxxxxx" <Mick.Jordan@xxxxxxx>, Xen Developers List <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Design question for PV superpage support
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 02 Mar 2009 19:04:46 +0000
Cc:
Delivery-date: Mon, 02 Mar 2009 11:05:17 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <6cbe7598-fb2d-4f29-8ee4-4c6c2201ac94@default>
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>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcmbZ5M0ptG0GsGVRUqy7KBLfLNbMQAAi1LI
Thread-topic: [Xen-devel] Design question for PV superpage support
User-agent: Microsoft-Entourage/12.15.0.081119
On 02/03/2009 18:48, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

>> If you make this constraint then you risk creating domains
>> that you cannot
>> always conveniently restore. Obviously you would allocate 2MB extents
>> wherever possible, since that is the whole point of this
>> drawn out exercise.
> 
> Understood.  This is a case where convenience and the primary objective
> conflict.  I can't think offhand of a way to do it, but restoring
> or migrating a 2MB-assumed domain into an environment where the
> vast majority of 2MB pages are emulated should probably raise a
> bright red flag somehow.  Or there needs to be some tool that
> can at least be queried as to how many 2MB pages are being emulated.
> 
> But probably the right long-term answer is a 2MB Xen with a 2MB
> Linux when applications assume/prefer 2MB pages.

I'd certainly be okay with this new config option meaning 'must get 2MB
extents' for now. It can be improved if the apparent downsides bite in
practice.

 -- Keir



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

<Prev in Thread] Current Thread [Next in Thread>