Xen users - Mar 2007 - Dynamically assign Hardware Resources

Hi xen-users

from what I understood, RAM and the number of CPUs cannot be increased 
for a running guest, but decreased and re-increased later.

So in order to have some headroom later, I want to assign (ie) 2 VCPUs 
and 512 MB of RAM in the config file, but reduce those settings to 1 
VCPU and 256 MB at boot time. So if the machine requires more power, I 
can assign more RAM or one more VCPU later.

So what I''m thinking about is writing a startup script in order to do 
this if nothing like that is available yet. Another thing I want to 
integrate is to set sched-credit weight and cap at boot time.

It would be even nicer to have this in xm, but unfortunately, I am not a 
C-programmer myself.

Any thoughts/wishes about what else one might want to
do with such a script?

Regards
Dominik

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

> -----Original Message-----
> From: xen-users-bounces@lists.xensource.com 
> [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of 
> Dominik Klein
> Sent: 15 March 2007 10:02
> To: xen-users@lists.xensource.com
> Subject: [Xen-users] Dynamically assign Hardware Resources
> 
> Hi xen-users
> 
> from what I understood, RAM and the number of CPUs cannot be 
> increased 
> for a running guest, but decreased and re-increased later.
> 
> So in order to have some headroom later, I want to assign 
> (ie) 2 VCPUs 
> and 512 MB of RAM in the config file, but reduce those settings to 1 
> VCPU and 256 MB at boot time. So if the machine requires more 
> power, I 
> can assign more RAM or one more VCPU later.
For the memory assignment, there already are two different parameters,
maxmem and memory, so it shouldn''t be too difficult to set maxmem to a
larger amount than memory. I guess it would need implementing a new
variable in the config file, but that''s probably not really difficult.

Adding a "max vcpu" value would most likely require a little bit more
work, as you''d have to allocate the extra VCPU''s up-front in
the domain
creation, and just not set them to runnable. 
> 
> So what I''m thinking about is writing a startup script in order to
do
> this if nothing like that is available yet. Another thing I want to 
> integrate is to set sched-credit weight and cap at boot time.
> 
> It would be even nicer to have this in xm, but unfortunately, 
> I am not a 
> C-programmer myself.
xm is written in python, so you don''t need to know C (but I guess if
you
don''t know Python, that''s not really a help). 

However, some of the work described above would require changing the
libxc and perhaps even the core of the hypervisor to allow the
functionality to be implemented. 

--
Mats
> 
> Any thoughts/wishes about what else one might want to
> do with such a script?
> 
> Regards
> Dominik
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
> 
> 
> 


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

> For the memory assignment, there already are two different parameters,
> maxmem and memory, so it shouldn''t be too difficult to set maxmem
to a
> larger amount than memory. I guess it would need implementing a new
> variable in the config file, but that''s probably not really
difficult.
Okay. Thank you.
> Adding a "max vcpu" value would most likely require a little bit
more
> work, as you''d have to allocate the extra VCPU''s up-front
in the domain
> creation, and just not set them to runnable. 
> 
>> So what I''m thinking about is writing a startup script in
order to do
>> this if nothing like that is available yet. Another thing I want to 
>> integrate is to set sched-credit weight and cap at boot time.
>>
>> It would be even nicer to have this in xm, but unfortunately, 
>> I am not a 
>> C-programmer myself.
> 
> xm is written in python, so you don''t need to know C (but I guess
if you
> don''t know Python, that''s not really a help). 
True :(
> However, some of the work described above would require changing the
> libxc and perhaps even the core of the hypervisor to allow the
> functionality to be implemented. 
So I just started writing the (shell)script. I will post it here when I 
think it''s usable.

Regards
Dominik

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