lkml.org 
[lkml]   [2009]   [Aug]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH][v2.6.29][XEN] Return unused memory to hypervisor
Miroslav Rezanina writes:
> ----- Original Message -----
> From: "Jeremy Fitzhardinge" <jeremy@goop.org>
> To: "Miroslav Rezanina" <mrezanin@redhat.com>
> Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, "Gianluca Guida" <gianluca.guida@citrix.com>
> Sent: Thursday, August 20, 2009 6:39:02 PM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
> Subject: Re: [PATCH][v2.6.29][XEN] Return unused memory to hypervisor
>
> On 08/20/09 00:47, Miroslav Rezanina wrote:
> >> there is handled e820 map in guest. However, this patch informs
> >> hypervisor, that guest uses less memory than was assigned to it.
> >> If hypervisor is not informed, memory is reserved for guest that
> >> do not need it. If hypervisor is informed, he decrease memory
> >> reservation for guest and unused memory is marked as free
> >> for use by other guests.
> >>
> >
> > Yes. But the guest will modify its own e820 map for a number of
> > reasons; for example: reducing its own memory, or clearing a space for
> > the PCI hole. In general we want to free any underlying pages which
> > don't correspond to E820_RAM regions.
> >
> > J
>
> I agree. However, I'm not sure if xen supports such a precise handling.

Xen will just get a list of mfn to remove from the domain. That is
precise enough. The scenario Jeremy is describing does happen,
especially in dom0 kernels.

G.


\
 
 \ /
  Last update: 2009-08-21 14:19    [W:0.067 / U:0.756 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site