Note about ch05 mps support (#324)

ch05/01_main-chapter-code/ch05.ipynb

@@ -1142,6 +1142,20 @@
    ],
    "source": [
     "device = torch.device(\"cuda\" if torch.cuda.is_available() else \"cpu\")\n",
+    "\n",
+    "# Note:\n",
+    "# Uncommenting the following lines will allow the code to run on Apple Silicon chips, if applicable,\n",
+    "# which is approximately 2x faster than on an Apple CPU (as measured on an M3 MacBook Air).\n",
+    "# However, the resulting loss values may be slightly different.\n",
+    "\n",
+    "#if torch.cuda.is_available():\n",
+    "#    device = torch.device(\"cuda\")\n",
+    "#elif torch.backends.mps.is_available():\n",
+    "#    device = torch.device(\"mps\")\n",
+    "#else:\n",
+    "#    device = torch.device(\"cpu\")\n",
+    "\n",
+    "\n",
     "model.to(device) # no assignment model = model.to(device) necessary for nn.Module classes\n",
     "\n",
     "\n",
@@ -1308,6 +1322,11 @@
     }
    ],
    "source": [
+    "# Note:\n",
+    "# Uncomment the following code to calculate the execution time\n",
+    "# import time\n",
+    "# start_time = time.time()\n",
+    "\n",
     "torch.manual_seed(123)\n",
     "model = GPTModel(GPT_CONFIG_124M)\n",
     "model.to(device)\n",
@@ -1318,7 +1337,13 @@
     "    model, train_loader, val_loader, optimizer, device,\n",
     "    num_epochs=num_epochs, eval_freq=5, eval_iter=5,\n",
     "    start_context=\"Every effort moves you\", tokenizer=tokenizer\n",
-    ")"
+    ")\n",
+    "\n",
+    "# Note:\n",
+    "# Uncomment the following code to show the execution time\n",
+    "# end_time = time.time()\n",
+    "# execution_time_minutes = (end_time - start_time) / 60\n",
+    "# print(f\"Training completed in {execution_time_minutes:.2f} minutes.\")"
    ]
   },
   {