Created attachment 120923 [details] [review]
fix long buffer wait times observed in trace

Hi pat, thanks for following up with this!

On Tonga, this trace runs into a variant of the compiler error you mentioned
earlier in the bug report due to limited SGPRs. This is something we still need
to address.

On Carrizo, I can run the trace and I notice an obvious buffer wait time
problem. Please try the quick-and-dirty patch I've attached. The trace is still
slow for me, but (a) it's a trace and (b) it's not a dGPU part, so I'd be
interested to hear how the in-game performance is for you with the patch.