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%100
(2)
Where,
represents the average time a physical machine requires to finalize a
CPU intensive workload in the execution conditions set for the test. On the other
hand,
represents the average time the same physical machine requires to
conclude the same CPU intensive workload in the absent of virtual machines (the
amount of processes being executed by the end-user during the test is constant).
40%
30%
1 VM
2 VM
3 VM
4 VM
20%
10%
0%
1
2
3
4
5
6
7
8
User processes
Fig. 6.
Intrusiveness of a Desktop Grid system in relation to the performance expected by an
end-user using an Intel Core i7-4770 processor
In Figure 6,
the solid line at bottom represents the intrusiveness caused by the ex-
ecution of a virtual machine assigned with a single CPU core. Indeed, its execution
can be categorized as non-intrusive since the degradation an end-user perceives on the
performance delivered by the processor remains below 10%. These conclusions can
be extended to scenarios with two virtual machines only when the end-user is not
executing CPU intensive workloads (i.e. by using 1 or 2 CPU cores). Similarly, when
the end-user is executing CPU intensive workloads (i.e. by using 7 to 8 CPU cores)
the results show that intrusiveness generated by Desktop Grids is below 10%. How-
ever, in the latter case, all the virtual machines in execution are not assigned with
processor resources thus severely decreasing its performance.
According to the results presented above, the following policy is proposed for the
non-intrusive opportunistic use of desktops based on the Intel Core i7-4770 architecture:
1.
In the absent of an end-user: opportunistically harvest all the computing resources.
2.
In presence of an end-user that is not executing CPU intensive workloads (i.e. by
using 1 or 2 CPU cores on average): opportunistically harvest up to 2 CPU cores.
3.
In presence of an end-user that is executing CPU intensive workloads (i.e. by using
2 to 6 CPU cores on average): opportunistically harvest 1 CPU core to diminish in-
trusiveness up to 10% or to exploit 2 CPU cores in order to decrease intrusiveness
up to 15%.
4.
In presence of an end-user that is using the entire processing resources (i.e. by us-
ing 7 to 8 CPU cores on average): opportunistically harvest as many idle resources
as available (even though they will be very limited to low-priority processes).
