Now within Mesa Git is MP performance counter support for the GK110, a.k.a. the GeForce GTX 780, Titan, K20, etc. The support landed here and while it's in place, it's currently not enabled by default: you must set the NVF0_COMPUTE=1 environment variable for enabling this experimental feature.
However, once enabled, you can take advantage of the exposed performance counters via the Gallium HUD, GL_AMD_performance_monitor OpenGL extension, etc. This support comes months after Pitoiset added this support to Fermi GPUs and some support for NV50. He also did some restructuring this week of the Nouveau NVC0 MP counters / driver metrics code and other improvements.