HIP: record direct atomic PSF timings

README.md

@@ -41,7 +41,10 @@ fallbacks remain CPU reference evaluations, with an ordered HDR transfer before
 and after each fallback. A HIP initialization, upload, kernel, or download
 error terminates the render; it never switches to the CPU backend silently.
 Use `make PSF_BACKEND=hip SPACETIME=minkowski hip-psf-test` for the small
-GPU-vs-CPU cache-HDR regression.
+GPU-vs-CPU cache-HDR regression. HIP renders also report event, batch, H2D,
+kernel, and HDR-download timing after each frame. To bound diagnostic-event
+storage, the report times at most the first 64 batches and labels the timed
+batch count explicitly; the event and total-batch counts are not sampled.
 
 ## Movie PNG sequence (Phase A)