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

[ko0nz <yesiko0nz@xxxxxxxxx>]

Hi,

It's strange for me.
I've got 8Go of RAM.
I've defined 1024M to Dom0 on the boot (/boot/grub/menu.lst)
...
kernel          /xen-3.1.0.gz dom0_mem=1024M console=vga
...

I've got some Guests with some Go of RAM et it still remain a lot of
RAM to use that i attibue to the news guests.
But the problem that when i tried to create it, i had this error:

# xm create toto.cfg
Using config file "/etc/xen/toto.cfg".
Error: I need 1073152 KiB, but dom0_min_mem is 200704 and shrinking to
200704 KiB would leave only 675672 KiB free.

# cat /etc/xen/toto.cfg
---
memory  = '1048'
---

If i shutdown one of my other guest, it will ok.
It's strange since i defined 1Go to Dom0, i get only 853Mo
# free -mo

             total       used       free     shared    buffers     cached
Mem:           853        190        662          0         23         32


Would someone explain me about this?
i'm with Debian Etch, Xen 3.1, 8Go RAM.

Thank you in advance.

On Thu, Jun 19, 2008 at 4:24 AM, Mark Williamson
<mark.williamson@xxxxxxxxxxxx> wrote:
> That said, I think many people find that for a minimal dom0, not doing much
> other work about 256MB is a reasonable amount of memory.  Maybe you'd want to
> go to 512MB if you had many guests and / or memory to spare.  dom0's
> requirements aren't extravagent, as long as you're not running loads of
> things in it (which on a server you shouldn't, for security reasons).
>
> Of course if you start running X and a modern desktop, you can expect dom0 to
> have significantly higher memory requirements, just as a normal machine
> would ;-)
>
> Cheers,
> Mark
>
> On Monday 16 June 2008, Sandor W. Sklar wrote:
>> On Jun 15, 2008, at 7:37 PM, Tim Post wrote:
>> > On Sun, 2008-06-15 at 17:45 -0700, Sandor W. Sklar wrote:
>> >> Well, of course, the amount of memory that a dom0 needs depends upon
>> >> the service running within it.  I guess I didn't word my question
>> >> explicitly enough.  Is there a formula for determine how much
>> >> memory a
>> >> dom0 might need, given a system with X amount of RAM, and X number of
>> >> guests, assuming there are no other services running in the dom0?
>> >
>> > You are hoping to calculate the best possible density? I.e. give dom-0
>> > xx MB per pv guest, xx MB per HVM guest?
>>
>> Indeed, exactly!  Not exact numbers, but a guideline that would let me
>> maximize the memory available to guests without running the risk of
>> starving the dom0.
>>
>> > Even that is too broad to really pin down, it would really depend on
>> > what you give the guests and how much they exercise the disks.
>>
>> OK, thanks, I guess I assumed as much, given that if such information
>> existed, Google would have told me.  :-)
>>
>>       -s-
>>
>>
>> _______________________________________________
>> Xen-users mailing list
>> Xen-users@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-users
>
>
>
> --
> Push Me Pull You - Distributed SCM tool (http://www.cl.cam.ac.uk/~maw48/pmpu/)
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users
>

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users