Virtual Scalability: Charting the Performance of Linux in a Virtual World

Many past topics at Ottawa Linux Symposium have covered Linux Scalability. While still quite valid, most of these topics have left out a hot feature in computing: Virtualization. Virtualization adds a layer of resource isolation and control that allows many virtual systems to co-exist on the same physical machine. However, this layer also adds overhead which can be very light or very heavy. We will use the Xen hypervisor, Linux 2.6 kernels, and many freely available workloads to accurately quantify the scaling and overhead of the hypervisor. Areas covered will include: (1) SMP Scaling: use several workloads on a large SMP system to quantify performance with a hypervisor. (2) Performance Tools: discuss how resource monitoring, statistical profiling, and tracing tools work differently in a virtualized environment. (3) NUMA: discuss how Xen can best make use of large system which have Non-Uniform Memory Access.