Analyzing PAPI Performance on Virtual Machines

Performance Application Programming Interface (PAPI) aims to provide a consistent interface for measuring performance events using the performance counter hardware available on the CPU as well as available software performance events and off-chip hardware. Without PAPI, a user may be forced to search through specific processor documentation to discover the name of processor performance events. These names can change from model to model and vendor to vendor. PAPI simplifies this process by providing a consistent interface and a set of processor-agnostic preset events. Software engineers can use data collected through source-code instrumentation using the PAPI interface to examine the relation between software performance and performance events. PAPI can also be used within many high-level performance-monitoring utilities such as TAU, Vampir, and Score-P.

VMware® ESXiTM and KVM have both added support within the last year for virtualizing performance counters. This article compares results measuring the performance of five real-world applications included in the Mantevo Benchmarking Suite in a VMware virtual machine, a KVM virtual machine, and on bare metal. By examining these results, it will be shown that PAPI provides accurate performance counts in a virtual machine environment.