1. The Role of Virtualization in Exascale Production Systems Jack Lange Assistant Professor University of Pittsburgh

2. Where are exascale OSes headed? Linux is accepted on Petascale – More than 80% of Top500 – Significant push to run Linux on production systems Pros – Complex systems are easier to manage – Existing codebase – Familiar and portable environment Cons – Not as responsive to application requirements – Exascale is not a primary design goal Linux is great for Ops, but only OK for Apps

3. Lightweight Kernels (LWKs) What do Apps need? – Simple memory management with little to no overhead – Low noise characteristics – Ability to perform large “bulk” I/O – … Traditional strengths of Lightweight Kernel architectures – Application driven resource management Lightweight kernels still have utility – But probably not as the primary system OS – App selectable runtime environment Challenge – Can we provide a lightweight environment on a heavyweight OS?

4. Virtualization on Linux Bypass Linux management layers Palacios selectively takes over resource management – Memory, devices, CPUs – Repurpose existing mechanisms Allocate large chunks of resources and manage them internally Kernel module – Does not require kernel modifications – Implements lightweight interface – Compatible with CNL (~2.6.32) Available in Palacios 1.3 (Nov. 2011)

5. Virtualized Dual Software Stack Hardware Palacios VMM Lightweight Kernel Management Processes + System Daemons Linux Module Interface Linux derived Compute Node OS HPC Application Palacios Resource Managers LWKs manage large resource allocations from VMM Apps can choose which allocators/management layers to deploy on LWKs can be co-designed with Apps and deployed on production systems

6. Performance isolation Memory Performance (GB/s) Noise Comparison between native Linux and virtual LWK

7. Thank you Jack Lange – jacklange@cs.pitt.edu – http://www.cs.pitt.edu/~jacklange V3Vee Project – http://www.v3vee.org