1. Heterogeneous Chip Multiprocessor Design for Virtual Machines Dan Upton and Kim Hazelwood University of Virginia

2. Pairing CMPs and VMs Challenge for chip multiprocessors: exploiting all available thread-level parallelism Challenge for virtual machines: reducing overhead Our solution: moving the VM to a separate core – only give a VM core what the VM needs

3. Heterogeneous Chip Multiprocessors Applications have different needs –Ex: Cache performance, available ILP Heterogeneous CMPs can be used to meet design constraints –Ex: Size, power, cost

4. Virtual machines Many practical applications –Dynamic translation (legacy ISA support) –Security –Instrumentation –… HW OS AppVM App HW VM OS App Process VMs (Ex: Pin, JVM, Rosetta)System VMs (Ex: Xen, Transmeta)

5. Design Approach Characterize a VM’s microarchitectural performance Examine processor organization options Consider beneficial modifcations for support SimpleScalar-x86 Pin Application

6. Two Examples Comparison of branch behavior against benchmarks from SPECINT 2000 Comparison of cache performance Other experiments in paper

7. Example: Branch Prediction

8. Example: L1 Caches

9. Example: L2 Cache

10. Design Options Two basic classes: General Purpose 1 General Purpose 2 VM (other specialized) General Purpose VM General Purpose VM General Purpose VM General Purpose VM

11. Support Structures Application Core VM Core where to compile where to resume executing support for indirect branches Support for tasks normally handled in software

12. Related Work Hardware support for VMs (Trident, DAISY, Kim and Smith) Transmeta Java in hardware (picoJava, JOP)

13. Work in Progress Comparing similarity of Pin to other VM software Characterizing VM compilation, cache management