My friend has reverse-engineered the number of parameters and possibly their names. This is what we know:
// performance monitor
// RBBM, VAP, GA, SU, SC, RS, TX, US, ZB, FG, RB3D, GPIN
// these are most probably some gpu registers which
// knowledge would be very useful in this extension
// somehow it should be possible to access them directly
// through these functions (perfstudio can do that)
void glGenPerfMonitorsAMD (GLsizei n, GLuint *monitors);
void glDeletePerfMonitorsAMD (GLsizei n, GLuint *monitors);
void glBeginPerfMonitorAMD (GLint monitor);
void glEndPerfMonitorAMD (GLint monitor);
void glGetPerfMonitorGroupsAMD (GLint* nOut, GLsizei n, GLint* groups);
void glGetPerfMonitorCountersAMD (GLint group, GLint*nOut, GLint* data, GLsizei n, GLint* counters);
void glGetPerfMonitorCounterDataAMD (GLint monitor, GLenum type, GLint ct,GLint* data, GLint* data2);
void glSelectPerfMonitorCountersAMD (GLint monitor, GLint x, GLint group, GLsizei n, GLint* counters);
void glGetPerfMonitorCounterStringAMD (GLint group, GLint y, GLsizei n,GLint* nOut, GLbyte* buff);
void glGetPerfMonitorGroupStringAMDPROC (GLint group, GLint n, GLint* nOut,GLbyte* data);
void glGetPerfMonitorCounterInfoAMDPROC (GLint group, GLint counter, GLenum type,GLint* data);
Include this source code in GLIntercept, then run GPU PerfStudio while GLIntercepting your application and values of those parameters will be logged. There’s still a lot of work to be done and I don’t think I have enough time to play with it. This extension seems to be pretty low-level.