add external_benchmark_pyrender (#13378)

* add external_benchmark_pyrender

* can ctrlc it

* cpu_profile exists

test/external/external_benchmark_pyrender.py

@@ -0,0 +1,34 @@
+# benchmark speed of pyrender for all created UOps saved with TRACK_MATCH_STATS=2
+import functools, pickle
+from tinygrad.uop.ops import UOp, Ops
+from tinygrad.helpers import tqdm, temp, time_to_str, cpu_profile
+
+BENCHMARK_OPS = {Ops.INDEX, Ops.BUFFERIZE}
+
+@functools.cache
+def create_uop(a:int) -> UOp:
+  op, dtype, src, arg, *rest = trace.uop_fields[a]
+  return UOp(op, dtype, tuple(create_uop(s) for s in src), arg, *rest)
+
+if __name__ == "__main__":
+  # load rewrite trace
+  with open(temp("rewrites.pkl", append_user=True), "rb") as f:
+    trace = pickle.load(f)
+
+  # benchmark
+  result:list[tuple[str, int]] = []
+  try:
+    for steps in tqdm(trace.rewrites):
+      for r in steps:
+        for _,yn,_,__ in r.matches:
+          y = create_uop(yn)
+          if y.op in BENCHMARK_OPS:
+            with cpu_profile("pyrender") as e:
+              try: ren = y.render()
+              except Exception: ren = "PYRENDER_ERR"
+            result.append((ren, float(e.en-e.st)/1e6))
+  finally:
+    N = 10
+    print(f"Slowst {N} renders from {len(result)} samples:")
+    for ren,tm in sorted(result, key=lambda x:x[1], reverse=True)[:N]:
+      print(f"{time_to_str(tm).strip():<10s} {ren}")