Re: [Xen-users] Allocate more Memory than real

["Artur Baruchi" <mail.baruchi@xxxxxxxxx>]

I see now.
This balloon has the same behavior of ESX Balloon driver
(http://www.usenix.org/events/osdi02/tech/waldspurger/waldspurger_html/node6.html).

One thing that I noted is.. when a new guest domain is create, the
dom0 limit is changed to memory_size - vm_memory_size. When I destroy
this guest, the dom0 still has the new limit, this isnt changed back
to memory_size.

Thanks in advance,

Att.
Artur Baruchi


On Tue, Sep 9, 2008 at 7:52 PM, Steffen Heil <lists@xxxxxxxxxxxxxxx> wrote:
> Hi
>
>> Is possible in xen to allocate more memory to virtual machines than the
> real  memory?
>
> Yes and No.
>
> You can "prepare" domUs to use some amount of memory, and then assign it
> some lower memory.
>
> The sum of all "prepared" memory sizes MAY exceed the total amount of real
> memory.
> The sum of the assigned memory sizes MAY NOT exceed the total amount of real
> memory.
>
> Also note, that the dom0 itself also counts. (It usually is prepared to use
> ALL memory and only uses what's left from the domUs.)
>
> Also note, that "total or real memory" in this context always refers to the
> amount of memory you have physically installed MINUS the memory Xen itself
> needs/uses.
> So the sum of all running domains (including dom0) can never reach you
> physical memory limit.
>
> Regards,
>  Steffen
>
>

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