ARB_pipeline_statistics_query Now Implemented In Mesa
The ARB_pipeline_statistics_query extension was developed in part by Brian Paul, the creator of Mesa and VMware employee, along with AMD and NVIDIA. This extension adds new query types to allow applications to gain stats about different parts of the pipeline. The GL_ARB_pipeline_statistics_query can be used for finding out the number of vertices and primitives issued to the GL, number of times shaders were invoked, number of primitives emitted by a geometry shader, and other similar stats that can be useful for fine-tuning games and applications. This extension can be found documented at OpenGL.org.
Intel developers took care of the core work for getting ARB_pipeline_statistics_query and then they implemented it in their i965 DRI driver. Ilia Mirkin then took care of implementing it for the Mesa Gallium3D state tracker so the Nouveau, Radeon, and Softpipe drivers can expose this extension for the next version of Mesa.