[Xen-devel] Xen cpu Scheduling

[pak333@xxxxxxxxxxx]

Hi,

 

I have some questions on scheduling.

 

1. Suppose I give a VM 2 vcpus. When this VM gets scheduled will it always be given two pcpus or can it be given 1vcpu also sometimes.  For example if we have mutiple VMs running, and if a cpu gets freed up will my 2vcpu VM be scheduled on this single free cpu.  If a single cpu cna be given how is the cpu % calculated by xentop

 

2. If the 2vcpu is scheduled on two cpus, and one of its threads goes to sleep can that single thread be context swtiched out. or will it be kept spinning.

 

3. When xentop reports VM cpu% as say 167% what does that mean. is it the % of time for the 2 vcpus (that means the VM is using 167% of the 200% it was allotted, or is the 167% of the number of pcpus in the system), or is it 167% of the total number of vcpus.

 

Thanks much for answering my questions

 

- Prabha

 

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