as supports AMD's Lightweight Profiling (LWP)
instruction set, available on AMD's Family 15h (Orochi) processors.
LWP enables applications to collect and manage performance data, and react to performance events. The collection of performance data requires no context switches. LWP runs in the context of a thread and so several counters can be used independently across multiple threads. LWP can be used in both 64-bit and legacy 32-bit modes.
For detailed information on the LWP instruction set, see the AMD Lightweight Profiling Specification available at Lightweight Profiling Specification.