diff --git a/README.md b/README.md
index 31c13b5..bc6a2af 100644
--- a/README.md
+++ b/README.md
@@ -60,4 +60,4 @@ I briefly tried finetuning gpt2 a bit more on our OWT and didn't notice dramatic
 
 ## benchmarking
 
-For model benchmarking `bench.py` might be useful. It's identical what happens in `train.py` except we're measuring just the fwd+bwd+update time of the model on a fixed random batch of data.
+For model benchmarking `bench.py` might be useful. It's identical what happens in the meat of the training loop of `train.py`, but omits much of the other complexities.
diff --git a/bench.py b/bench.py
index 8356d21..c28d1df 100644
--- a/bench.py
+++ b/bench.py
@@ -1,7 +1,8 @@
 """
-A much shorter version of train.py for benchmarking the model
+A much shorter version of train.py for benchmarking
 """
-
+import os
+import numpy as np
 import time
 import torch
 from model import GPTConfig, GPT
@@ -14,6 +15,26 @@ torch.manual_seed(1337)
 batch_size = 8
 block_size = 1024
 
+# data loading init
+real_data = True
+if real_data:
+    dataset = 'openwebtext'
+    data_dir = os.path.join('data', dataset)
+    train_data = np.memmap(os.path.join(data_dir, 'train.bin'), dtype=np.uint16, mode='r')
+    def get_batch(split):
+        data = train_data # note ignore split in benchmarking script
+        ix = torch.randint(len(data) - block_size, (batch_size,))
+        x = torch.stack([torch.from_numpy((data[i:i+block_size]).astype(np.int64)) for i in ix])
+        y = torch.stack([torch.from_numpy((data[i+1:i+1+block_size]).astype(np.int64)) for i in ix])
+        x, y = x.to(device), y.to(device)
+        return x, y
+else:
+    # alternatively, if fixed data is desired to not care about data loading
+    x = torch.randint(50257, (batch_size, block_size), device=device)
+    y = torch.randint(50257, (batch_size, block_size), device=device)
+    get_batch = lambda split: (x, y)
+
+# model init
 gptconf = GPTConfig(
     block_size = block_size, # how far back does the model look? i.e. context size
     n_layer = 12, n_head = 12, n_embd = 768, # size of the model
@@ -22,9 +43,6 @@ gptconf = GPTConfig(
 model = GPT(gptconf)
 model.to(device)
 
-x = torch.randint(50257, (batch_size, block_size), device=device)
-y = torch.randint(50257, (batch_size, block_size), device=device)
-
 optimizer = model.configure_optimizers(weight_decay=1e-2, learning_rate=1e-4, betas=(0.9, 0.95))
 
 burn_in = 10 # number of burn in steps where we don't measure time
@@ -34,8 +52,9 @@ for k in range(num_steps):
     if k == burn_in:
         t0 = time.time() # start the timer
 
+    X, Y = get_batch('train')
     with torch.autocast(device_type='cuda', dtype=torch.bfloat16):
-        logits, loss = model(x, y)
+        logits, loss = model(X, Y)
 
     optimizer.zero_grad(set_to_none=True)
     loss.backward()