[Intel-gfx] [PATCH 1/2] drm/i915/tracepoints: Don't compile-out low-level tracepoints

[Egor Suldin]

Hi!
I use GPUVis and now Intel Vtune Profiler. These tools don't work 
out-of-the-box on all Linux based systems for Intel integrated graphics.
It is needed to rebuild at least i915 module. And each time when the 
kernel is updated it is needed to rebuild i915 module again.

 > No numbers from (micro-)bechmarks showing how small the impact of doing
 > this is? I thought John was compiling this data. It will be just a no-op
 > on the fast path, but a bit more generated code.
Have you collected the results? If not, I've done it for you:
Benchmark for Metro 2033 Last Light Redux:
w/o events:
1st run aver. fps: 36.06
2nd run aver. fps: 35.87
w events:
1st run aver. fps: 36.05
2nd run aver. fps: 35.92

There is no difference. It was run on Intel Core i9-9900K CPU @ 3.60GHz 
on integrated graphics.

 > Assuming that will be fine, the only potentially problematic aspect that
 > comes to mind is the fact meaning of these tracepoints is a bit
 > different between execlists and guc. But maybe that is thinking to low
 > level (!) - in fact they are in both cases at points where i915 is
 >passing/receiving requests to/from hardware so not an issue?
In my view, it is not an issue. The real issue now that you cannot 
collect performance results for Intel GPU
on Linux systems without rebuilding the i915 module. You cannot debug 
performance problems
on the system even if you use tools from Intel. Do you have ETA to 
accept this patch?

Thanks,
Egor