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xen-users
Re: [Xen-users] 2 DomU and 2 4-cores CPU
The question you ask is a multidimensional optimization of a function
that has discontinuities and depends on both the nature of workloads
and the specifics of the CPUs.
What specific CPUs are you referring to?
Basic rule:
1. Dedicate a single core to dom0
(a core meaning real core not a hyperthread path that looks like a
core to an OS).
2. Limit dom0 to 512mb or less memory
That's it.
Anything else is likely talk and theorizing that is simply wasting
air. Far better to deploy your rotliafs and start testing. I'll be
amazed if configuration of the credit scheduler has a substantive
impact at this point.
Peter
Sent from my iPhone
On Apr 9, 2010, at 3:27 AM, Michael Schmidt
<michael.schmidt@xxxxxxxxxx> wrote:
Hi,
Xen has different CPU schedulers. The default is the credit
scheduler - this is a "fair" scheduler.
Here cou can read more about it:
http://wiki.xensource.com/xenwiki/CreditScheduler
Mit freundlichen Gruessen / Best Regards
Michael SchmidtAm 09.04.10 09:09, schrieb L.M.J:
On Fri, 02 Apr 2010 10:29:53 +0200, Michael Schmidt
<michael.schmidt@xxxxxxxxxx> wrote:
Hi,
you can assign all DomUs all cores.
In the case of 100% utilization of both DomUs, the xen-scheduler
provides 50% CPU time from all the CPUs for each DomU.
If one DomU idles and the other one, need 100% CPU, it will get the
power of all the 8 Cores.
Thanks Michael for your fast reply. I would like to share what I've
heard
from Vmware : when you assigned 4 CPU to a VM, Vmware wait to have
4 cores
free at the same time before give them to the VM which could slow
down your
VM instead of speed up.
Is there the same issue with Xen ?
L.M.J schrieb:
Hi,
With my college, I was wondering what is the best optimization
for our
setup. I've got 2 VM with 16GB of RAM and 4 vCPU to each one. My
server
got 2 CPU with 4 cores inside (makes 8 CPU). What produce the best
performance :
1) Give ALL cpu to my 2 VM and each ones will take its 4 vCPU
where it
can
2) Give CPU 0-3 to VM1 and CPU 4-7 to VM2 : each vm own the 4
cores
from 1 CPU
3) Give CPU 0,1,4,5 to VM1 and 2,3,6,7 to VM2 : mix cores
between the
both CPU
Thanks by advance for any information or point me to any docs
talking
about this !
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