Re: [Xen-users] Doubt on XEN memory management: please clarify

[Flavio <fbcyborg@xxxxxxxxx>]

On 15 April 2012 23:56, Simon Hobson <linux@xxxxxxxxxxxxxxxx> wrote:
> That sounds about right. Dom0 will only "see" the RAM that's assigned to it,
> you need to use the Xen tools (eg xentop) to see how much memory is assigned
> to each domain and how much is free.
> What you are probably missing is that Dom0 is itself a guest virtual machine
> running under the Xen hypervisor - it differs from a DomU PV guest mainly in
> having privileged Âaccess to communicate with the hypervisor and hardware.
> But since it is itself a guest, it only has access to resources (in this
> discussion, RAM) given to it by the hypervisor. The dom0 memory allocation
> statements are instructions to the hypervisor, not Dom0.
OK Simon. Thanks a lot.
This clarified me the doubt I had on this topic.
To be honest I did know that the dom0 is a guest VM, but I was confusing between
the hypervisor and the dom0 itself. It should be totally clear to me now.

So, now the problem is that until the memory issue problem won't be solved,
it will be a sort of trouble to manage XEN with its domUs. I think
everyone would
have some pain if its system shows 600MB for free, when it has at least 7GB.

> I don't personally know of any good books - but then books are a tricky
> thing in this sort of area as they have a limited shelf life before the
> software moves on.
I perfectly agree with you. This is true in most of the field within computer
research and IT technologies, but it was worth to ask!

Thank you very much,

Flavio

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