AutoBatch improve cache clearing (#16744)

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

ultralytics/utils/autobatch.py

@@ -69,7 +69,7 @@ def autobatch(model, imgsz=640, fraction=0.60, batch_size=DEFAULT_CFG.batch):
     batch_sizes = [1, 2, 4, 8, 16]
     try:
         img = [torch.empty(b, 3, imgsz, imgsz) for b in batch_sizes]
-        results = profile(img, model, n=3, device=device)
+        results = profile(img, model, n=1, device=device)
 
         # Fit a solution
         y = [x[2] for x in results if x]  # memory [2]
@@ -89,3 +89,5 @@ def autobatch(model, imgsz=640, fraction=0.60, batch_size=DEFAULT_CFG.batch):
     except Exception as e:
         LOGGER.warning(f"{prefix}WARNING ⚠️ error detected: {e},  using default batch-size {batch_size}.")
         return batch_size
+    finally:
+        torch.cuda.empty_cache()

ultralytics/utils/torch_utils.py

@@ -643,7 +643,8 @@ def profile(input, ops, n=10, device=None):
         f"{'Params':>12s}{'GFLOPs':>12s}{'GPU_mem (GB)':>14s}{'forward (ms)':>14s}{'backward (ms)':>14s}"
         f"{'input':>24s}{'output':>24s}"
     )
-
+    gc.collect()  # attempt to free unused memory
+    torch.cuda.empty_cache()
     for x in input if isinstance(input, list) else [input]:
         x = x.to(device)
         x.requires_grad = True
@@ -677,8 +678,9 @@ def profile(input, ops, n=10, device=None):
             except Exception as e:
                 LOGGER.info(e)
                 results.append(None)
-            gc.collect()  # attempt to free unused memory
-            torch.cuda.empty_cache()
+            finally:
+                gc.collect()  # attempt to free unused memory
+                torch.cuda.empty_cache()
     return results