Add nsys probe scripts for ClusterFinderCUDA

Per-engine GPU time, duty cycle and roofline on the campaign configs
(3x3 cap 3000, 9x9 cap 1700, 1 and 4 streams, 20k frames).

python/tests/perf/nsys_kernel_probe.py

@@ -0,0 +1,47 @@
+"""The process nsys traces: train the pedestal, run one batched pass, exit.
+
+    nsys_kernel_probe.py <n_streams> <n_frames> <cluster_dim> <cap> <batch>
+
+Run by run_probes.py; run directly only under `nsys profile --trace=cuda`.
+The wall time printed is profiler-inflated and is not a throughput number.
+"""
+import sys
+import time
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent))
+import common  # noqa: E402  (puts the build dir on sys.path)
+
+from aare import File, ClusterFinderCUDA  # noqa: E402
+
+n_streams, N, cdim, cap, batch = (int(a) for a in sys.argv[1:6])
+
+f = File(common.DATA_FILE)
+pd = File(common.PEDESTAL_FILE)
+
+cf = ClusterFinderCUDA((f.rows, f.cols), (cdim, cdim), n_sigma=common.N_SIGMA,
+                       max_clusters_per_frame=cap, n_streams=n_streams)
+for _ in range(common.N_PEDESTAL_FRAMES):
+    cf.push_pedestal_frame(pd.read_frame().copy())
+
+data = f.read_n(N)
+cf.register_input_buffer(data)
+# Pin the output slots without processing frames: a warm-up pass would advance
+# the device pedestal and make this run incomparable with the next.
+cf.reserve_output_slots(cf.chunk_size_for(min(N, batch)))
+
+t0 = time.perf_counter()
+n = 0
+for start in range(0, N, batch):
+    for cv in cf.find_clusters_batched(data[start:min(start + batch, N)],
+                                       first_frame=start):
+        n += cv.size
+t = time.perf_counter() - t0
+cf.unregister_input_buffer()
+
+h2d = f.rows * f.cols * 2
+slot = 2 + 2 + cdim * cdim * 4  # x, y (uint16) + data (int32)
+print(f"n_streams={n_streams}  N={N}  cluster={cdim}x{cdim}  cap={cap}  batch={batch}")
+print(f"  H2D/frame={h2d:,} B   D2H/frame={cap * slot:,} B "
+      f"({slot} B/slot, {100 * n / N / cap:.0f}% filled)")
+print(f"  wall={t:.3f}s  ({N / t:.0f} FPS, profiler-inflated)  clusters/frame={n / N:.2f}")