Multicore memory subsystem aspects and its influence on the performance of modern VMMs

The latest multicore processors brought important features for virtualized environments. They added a shared cache level, improving communication among cores, and nested paging support, which enable address translation without intervention of the virtual machine monitor (VMM). The address translation is more expensive when using nested paging, because it is necessary to traverse both guest page tables and VMM managed ones. One way to mitigate this is employing large pages in the mapping of virtual machine memory, reducing the number of translation steps. The purpose of this study is to investigate the influence of memory subsystem on virtual machines using virtual multiprocessing on multicore processors, to determine the set of characteristics that offer better performance. Employing parallelizable tasks, we analyzed the presence of shared cache between cores and the use of large pages by the VMM, comparing the effects of them under shadow and nested paging.