Re: [Xen-users] Why limit dom0's memory?

["Todd Deshane" <deshantm@xxxxxxxxx>]

On Sat, Jun 14, 2008 at 11:58 AM, Gastón Keller <gastonkeller@xxxxxxxxx> wrote:

On Sat, Jun 14, 2008 at 11:47 AM, Sandor W. Sklar <ssklar@xxxxxxxxxxxx> wrote:
>
> On Jun 14, 2008, at 5:35 AM, Gastón Keller wrote:
>
>>>  I have this wrong, or am I not understanding something?
>>
>> AFAIK what some people is doing is setting a level of memory for Dom0
>> for it to never go down that level (giving memory to the guests). That
>> is, if you set the memory to 1 GB, Dom0 will allocate all your memory
>> except for that 1 GB. It's a way of ensuring that Dom0 will never run
>> out of memory.
>
> Ah, thanks!  That makes sense.  Is there some formula for determining how
> much memory a dom0 might need, given a system with X amount of RAM, and X
> number of guests?

I wouldn't know what to tell you. Sorry! =)

I don't think there is a magic formula like that anyway.

It will depend on what you are using the system for. You should try to minimize what
is run in dom0. You should make sure that your guests have sufficient memory so
that they are not thrashing the disk. All this depends on the load your system is
going to take on. Bottom line is that not running out of memory on Dom0 is first
priority, then guests. Always try to give some wiggle room if possible and do lots
of testing if you can.

For more information on Xen in book format, take a look at "Running Xen: A Hands-on
Guide to the Art of Virtualization" (http://runningxen.com)
 
Cheers,
Todd
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