[Xen-users] Machine time delay in guest domains (Full virtualization)

["KUMIKO GOTO" <gotou.kumiko@xxxxxxxxx>]

Hi,

I have one question about machine time delay in guest domains (full 
virtualization).

In order to evaluate cpu performance, I applied "SPEC CPU2006" and found 
that
machine time of guest domains is severely delayed from actual time.
->Actual test time : test time measured in guest domains = 4:1
(e.g., Actual test time =40 min, test time measured in guest domain time 
=10 min)

I think that there is some relationship between the number of domains and 
cores.
(please see the following results)

Does anyone know why this kind of time delay occurs in Xen? 

------------------------------------------------------
<<Environment>>
-Host machine has 2 cores (core number 0-1)
-Guest OSs: Full virtualization

*test 1
4 domains share 2 core (each domain has 2 vcpu)
->result: actual test time : test time measured in guest domains = 4:1

*test 2
2 domains share 1 core and the other 2 domains share the other 1 core. 
->result: actual test time : test time measured in guest domains = 2:1
------------------------------------------------------

Thanks for your kindness.

Best,

-Kumiko
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