CPU Demand takes different time with same parameters
Using the attached protocom model on the testbed from Steffen gives strange results.
The assumed time for one scenario execution is 200ms.
Executed in a closed workload I get 192ms which is good. Executed in an open workload I get the 192ms during warm-up and afterwards I get results of 260-350ms.
java version "1.6.0_20"
OpenJDK Runtime Environment (IcedTea6 1.9.7) (suse-1.2.1-x86_64)
OpenJDK 64-Bit Server VM (build 19.0-b09, mixed mode)
3 Virtual CPUs mounted as real CPUs not as kernels (multithreading disabled)
8192MB RAM, 2*12 GB HDDs
openSuse 11.3 with kernel 220.127.116.11-0.5-desktop
Protocom process pinned to one cpu
One server running RMI Registry, System and Usage Scenario, the other one the resource environment
This is no bug, but a feature of ProtoCom - it measures the correct things! The virtual environment you used has a power management that dynamically decreases the CPU's clock rate (Intel's "Enhanced SpeeStep technology" is enabled). Deactivating this feature results in the results you expected, leaving it measures this "reconfiguration" effect. It depends on your use case whether you should activate the feature.