[one-users] Some questions about overcommitment in OpenNebula 4.2 using KVM

[Gerry O'Brien]

On 16/10/2013 17:19, Michał Madziar wrote:
> On 2013-10-16 14:42, Gerry O'Brien wrote:
>> Hi,
>>
>>      Do you know if the CPU parameter has any effect on the amount of
>> real cpu used, e.g. if I set the CPU parameter to 0.1 will this limit
>> the actual cpu usage?
> libvirt uses cgroups, so yes, it does.
cgroups do not seem to be enabled with kvm. Am I correct in assuming this?
>
>>      Also, can the monitor driver be  configured to report multiples of
>> memory and allow memory overcommitment in the same way?
> Just assign whatever you want to $total_memory in kvm.rb, but keep in
> mind that if ballooned/deduplicated pages will start to differ either
> swap will be used (which will probably kill the host) or oomkiller will
> kick in.
>
> Example:
> $total_cpu = 2000
> $free_cpu = $total_cpu - $used_cpu
> $total_memory = $total_memory.to_i+$free_memory.to_i
> $free_memory = $total_memory - $used_memory.to_i
> print_info("HYPERVISOR","kvm")
> #...
>
> Dashboard charts will look strange but it seems to work.


Hi,

This didn't work for me. I'm running 4.2. The scheduler has a capacity 
test (see below). Any idea where the code for "get_requirements" lives?



// -----------------------------------------------------------------
// Check host capacity
// -----------------------------------------------------------------

vm->get_requirements(vm_cpu,vm_memory,vm_disk);

if (host->test_capacity(vm_cpu,vm_memory,vm_disk) == true)
{
vm->add_host(host->get_hid());

n_hosts++;
}
else
{
ostringstream oss;

oss << "VM " << oid << ": Host " << host->get_hid()
<< " filtered out. Not enough capacity.";

NebulaLog::log("SCHED",Log::DEBUG,oss);
}






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-- 
Gerry O'Brien

Systems Manager
School of Computer Science and Statistics
Trinity College Dublin
Dublin 2
IRELAND

00 353 1 896 1341