Xen users - May 2012 - Allocating memory and cpu to Domain-0

Hi,
It seems that allocating dedicated memory and cpu(s) is recommended
for IO intensive guests (why would I not assume it won''t be?)

How can I calculate the amount of memory and cpu to allocate for Dom-0?
Is there a formula we can use for this?

If there is no known defined formula, isn''t it better to allocate
using xm m-set and vcpu-set, versus on boot-time? So you can at least
adjust when needed ?

Thanks.
Lloyd

On Tue, May 15, 2012 at 3:07 PM, Lloyd Dizon <thecarrionkind@gmail.com>
wrote:
> How can I calculate the amount of memory and cpu to allocate for Dom-0?
> Is there a formula we can use for this?
I found some information that explains this a bit. But still doesn''t
make sense:

http://www.novell.com/support/kb/doc.php?id=3559698

Basically the article above says that:

the total system memory minus the amount of memory assigned to dom0
equals the amount required by the hypervisor

TotalMem - Dom0Mem =  memory for Hypervisor.

but Hypervisor /= Dom0.


So the question still remains, how do you calculate memory for Dom-0 ?


Other than that several interesting things recommended by the article:
"Lock down" the amount of memory assigned to dom0.
Disable ballooning
Do not restrict dom0 to a single VCPU
Only use Logical Volume Manager (LVM) on Dom0 or DomU, but not both