Guest PMU (Performance Monitoring Unit) currently exists in the form of an out-of-tree patchset.
See the Forum 2011 presentation about the state as of August 2011.
Version 1 Architectural PMU on Intel and AMD hosts is implemented and works.
Guest visible features
- Implement Version 2 Architectural PMU - allows faster switch times using PERF_GLOBAL_ENABLE MSR
- Implement Version 3 Architectural PMU
- Model specific PMU - allows access to more events and support for more tools; but restricts live migration capabilities
- Need per-event validation to avoid leaking socket-wide or core-wide information
- PEBS - Preceise Event Based Sampling - allows examining program state
- BTS - Branch Trace Store - allows tracing program execution accurately
- Update Joerg Roedel's exclude_guest/exclude_host patchset to support Intel hosts, using vmx's ability to load PERF_GLOBAL_ENABLE on vmentry/vmexit
- Investigate reports that enabling the guest PMU reduces performance
- Update the perf_event subsystem to make use of the PERF_GLOBAL_ENABLE MSR to speed up context switching, on both guest and host
- Check whether perf_event does unnecessary RMW operations on MSRs, which are significantly slow in a guest
- Add a paravirt batch MSR read/write facility, update perf to use it when available
Guest PMU: git://github.com/avikivity/kvm.git pmu
exclude_host: git://github.com/avikivity/kvm.git perf-guest-counting