If you have a reasonably new computer with a multi-coreprocessor and want to be able to run parallel programs across multiplecores, you can tell VirtualBox to allow the VM to use additionalcores. To do this, open the VirtualBoxSettings. Under System, click the Processortab, then use the slider to set the number of processors the VM willsee. Note that some older multi-core processors do not support thenecessary extensions for this, and on these machines you will only beable to run the VM on a single core.