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/
Home Products Support Community News


RE: [Xen-devel] scrubbing free'd pages

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxxx>, James Harper <james.harper@xxxxxxxxxxxxxxxx>, Rafal Wojtczuk <rafal@xxxxxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] scrubbing free'd pages
From: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
Date: Tue, 25 May 2010 14:48:22 +0100
Accept-language: en-US
Acceptlanguage: en-US
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Tue, 25 May 2010 06:49:33 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <C82191B4.1540A%keir.fraser@xxxxxxxxxxxxx>
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: <AEC6C66638C05B468B556EA548C1A77D01996B12@trantor> <C82191B4.1540A%keir.fraser@xxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-topic: [Xen-devel] scrubbing free'd pages
> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-
> bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Keir Fraser
> Sent: 25 May 2010 14:40
> To: James Harper; Rafal Wojtczuk
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] scrubbing free'd pages
> On 25/05/2010 14:33, "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
> wrote:
> >> Other memory pages the domain freeing the
> >> pages must scrub them itself before freeing them back to Xen.
> >
> > Is that true for a HVM domain making a decrease_reservation
> hypercall?
> > If so I should modify my code accordingly...
> Yes you should.
> > it also means I need to
> > know if the page I'm decreasing is an unpopulated PoD page or not
> too.
> Certainly you could avoid it in that case. Actually I think the PoD
> code can
> detect and reclaim allocated-but-zeroed pages however. But not sure
> if you
> really have to rely on that or not.

Yes, that's true, but it would be better if we didn't have to scrub pages and 
cause a populate immediately before an invalidate.


Xen-devel mailing list