The open-source PMU-Tools package for Linux allows for a number of performance monitoring units / performance counters to be tapped on the latest Intel processors. PMU-Tools builds on top of the Linux kernel's perf subsystem to offer a wealth of information to developers.
PMU-Tools for performance monitoring unit measuring is largely written by Intel's Andi Kleen, including the ocperf and toplev components of it.
For those wanting to learn all about PMU-Tools for exploring more of the hardware counters that can be utilized on the latest Intel CPUs, read Andi's pmu-tools part 1
and pmu-tools, part II: toplev
, which he wrote this weekend.