From: Dave McCracken <dcm@mccr.org>
To: Mick.Jordan@sun.com
Cc: Xen Developers List <xen-devel@lists.xensource.com>
Subject: Re: Design question for PV superpage support
Date: Mon, 2 Mar 2009 12:00:09 -0600 [thread overview]
Message-ID: <200903021200.09999.dcm@mccr.org> (raw)
In-Reply-To: <49AC1B22.50307@Sun.COM>
On Monday 02 March 2009, Mick Jordan wrote:
> On 03/02/09 08:43, Mick Jordan wrote:
> > On 03/02/09 05:54, Dave McCracken wrote:
> >> The solution I am working on for how to support Linux hugepages (Xen
> >> superpages) involves creating domains made up entirely of
> >> superpages. I can create a working domain with superpages and am in
> >> the process of supporting it in save/restore.
>
> I'm assuming that this means that everything is upgraded from 4K to 2MB.
> E.g. pfn 0 = 0, pfn 1 = 2MB., etc., and the mfn<->pfn maps also.
No, actually, it doesn't do that. The hypervisor allocates 2M pages, then
expands them into 4K pages for the mfn<->pfn maps, etc.
The only effective difference is that any given 2M-aligned range of pfns is
guaranteed to map to a contiguous 2M-aligned range of mfns. Therefore the
guest can safely allocate 2M pages.
Dave McCracken
Oracle Corp.
next prev parent reply other threads:[~2009-03-02 18:00 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-02 13:54 Design question for PV superpage support Dave McCracken
2009-03-02 13:58 ` Keir Fraser
2009-03-02 16:43 ` Mick Jordan
2009-03-02 17:06 ` Keir Fraser
2009-03-02 18:02 ` Mick Jordan
2009-03-02 17:29 ` Dave McCracken
2009-03-02 17:52 ` Keir Fraser
2009-03-02 18:03 ` Dan Magenheimer
2009-03-02 18:30 ` Keir Fraser
2009-03-02 18:46 ` Mick Jordan
2009-03-02 18:48 ` Dan Magenheimer
2009-03-02 19:04 ` Keir Fraser
2009-03-02 17:45 ` Mick Jordan
2009-03-02 17:54 ` Keir Fraser
2009-03-02 18:00 ` Dave McCracken [this message]
2009-03-02 18:14 ` Mick Jordan
2009-03-02 19:14 ` Dave McCracken
2009-03-03 1:37 ` Jeremy Fitzhardinge
2009-03-03 3:59 ` Mick Jordan
2009-03-03 14:33 ` Dan Magenheimer
2009-03-03 17:06 ` Mick Jordan
2009-03-03 17:23 ` Jeremy Fitzhardinge
2009-03-03 18:10 ` Keir Fraser
2009-03-03 17:28 ` Jeremy Fitzhardinge
2009-03-03 18:09 ` Dan Magenheimer
2009-03-03 17:26 ` Jeremy Fitzhardinge
2009-03-03 1:32 ` Jeremy Fitzhardinge
2009-03-03 1:15 ` Jeremy Fitzhardinge
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