experiments

c4gzparse_nanogpt.py

@@ -0,0 +1,56 @@
+import os
+from tqdm import tqdm
+import numpy as np
+import tiktoken
+import json
+import gzip
+
+enc = tiktoken.get_encoding("gpt2")
+
+if __name__ == '__main__':
+    # takes 54GB in huggingface .cache dir, about 8M documents (8,013,769)
+    dataset = []
+
+    with gzip.open("c4-train.00000-of-01024.json.gz", "r") as file:
+        while line := file.readline():
+            try:
+                dataset.append(json.loads(line))
+            except EOFError:
+                pass
+
+    # we now want to tokenize the dataset. first define the encoding function (gpt2 bpe)
+    def process(example):
+        ids = enc.encode_ordinary(example['text']) # encode_ordinary ignores any special tokens
+        ids.insert(0, enc.eot_token) # add the end of text token, e.g. 50256 for gpt2 bpe
+        # note: I think eot should be prepended not appended... hmm. it's called "eot" though...
+        out = {"ids": ids, "len": len(ids)}
+        return out
+
+    # tokenize the dataset
+    tokenized = [ process(x) for x in dataset ]
+    divider = len(tokenized) // 100
+    tokenized = {
+        "val": tokenized[:divider],
+        "train": tokenized[divider:]
+    }
+
+    # concatenate all the ids in each dataset into one large file we can use for training
+    for split, dset in tokenized.items():
+        arr_len = sum((d['len'] for d in dset))
+        filename = os.path.join(os.path.dirname(__file__), f'{split}.bin')
+        dtype = np.uint16 # (can do since enc.max_token_value == 50256 is < 2**16)
+        arr = np.memmap(filename, dtype=dtype, mode='w+', shape=(arr_len,))
+        total_batches = 1024
+
+        idx = 0
+        for d in tqdm(dset, desc=f'writing {filename}'):
+            arr[idx : idx + d["len"]] = d["ids"]
+            idx += d["len"]
+        arr.flush()
+
+    # train.bin is ~17GB, val.bin ~8.5MB
+    # train has ~9B tokens (9,035,582,198)
+    # val has ~4M tokens (4,434,897)
+
+    # to read the bin files later, e.g. with numpy:
+    # m = np.memmap('train.bin', dtype=np.uint16, mode='r')

compare_ckpts.py

@@ -0,0 +1,69 @@
+import torch
+from pathlib import Path
+from collections import defaultdict
+import matplotlib.pyplot as plt
+import torch.nn.functional as F
+
+def compute_differences(m1, m2):
+    groups = {"mlp.c_fc.weight": defaultdict(lambda: 0.0), "attn.c_attn.weight": defaultdict(lambda: 0.0)}
+    for k, v1 in m1["model"].items():
+        for cat in groups.keys():
+            if cat in k:
+                diff = torch.flatten(v1 - m2["model"][k])
+                #groups[cat]["l1"] += torch.linalg.norm(diff, dim=None, ord=1).item()
+                groups[cat]["l2"] += torch.linalg.norm(diff, dim=None, ord=2).item()
+                #groups[cat]["cosine"] += F.cosine_similarity(v1.flatten(), m2["model"][k].flatten(), dim=-1).item()
+    return groups
+
+def gradnorm(m):
+    x = 0
+    for key, state in m["optimizer"]["state"].items():
+        #x += torch.linalg.norm(state["exp_avg"], dim=None, ord=2).item()
+        x += torch.mean(state["exp_avg_sq"]).item()
+    return x
+
+def flatten(xs, out=None, prefix=""):
+    if out is None: out = {}
+    for k, v in xs.items():
+        longk = (prefix + " " + k).strip()
+        if isinstance(v, dict): flatten(v, out, longk)
+        else:
+            out[longk] = v
+    return out
+
+xs = []
+ys = defaultdict(list)
+for step in range(500, 3500, 500):
+    file = f"ckpt{step}.pt"
+    m_baseline = torch.load(Path("fixed-seed1") / file)
+    m_sameseed = torch.load(Path("fixed-seed1-1") / file)
+    m_sameseed2 = torch.load(Path("fixed-seed1-2") / file)
+    m_other = torch.load(Path("fixed-seed2") / file)
+    m_baseline_resumed = torch.load(Path("fixed-seed1-res1500") / file)
+    xs.append(step)
+
+    """
+    comparisons = {
+        "same seed": compute_differences(m_baseline, m_sameseed),
+        "same seed 2": compute_differences(m_baseline, m_sameseed2),
+        "same seed resume at 1500": compute_differences(m_baseline, m_baseline_resumed),
+        "other seed": compute_differences(m_baseline, m_other),
+    }
+    """
+    comparisons = {
+        "baseline": gradnorm(m_baseline),
+        "same seed": gradnorm(m_sameseed),
+        "same seed 2": gradnorm(m_sameseed2),
+        "other seed": gradnorm(m_other)
+    }
+    
+    for k, v in flatten(comparisons).items():
+        ys[k].append(v)
+
+plt.figure(figsize=(12, 10))
+plt.xlabel("step")
+plt.ylabel("gradnorm")
+for k, v in ys.items():
+    plt.plot(xs, v, label=k)
+plt.legend()
+plt.savefig("x.png")

config/train_gpt2.py

@@ -2,7 +2,7 @@
 # launch as the following (e.g. in a screen session) and wait ~5 days:
 # $ torchrun --standalone --nproc_per_node=8 train.py config/train_gpt2.py
 
-wandb_log = True
+wandb_log = False
 wandb_project = 'owt'
 wandb_run_name='gpt2-124M'
 

config/train_shakespeare_char.py

@@ -35,3 +35,4 @@ warmup_iters = 100 # not super necessary potentially
 # on macbook also add
 # device = 'cpu'  # run on cpu only
 # compile = False # do not torch compile the model
+compile = False

model.py

@@ -298,7 +298,7 @@ class GPT(nn.Module):
         flops_per_iter = flops_per_fwdbwd * fwdbwd_per_iter
         # express our flops throughput as ratio of A100 bfloat16 peak flops
         flops_achieved = flops_per_iter * (1.0/dt) # per second
-        flops_promised = 312e12 # A100 GPU bfloat16 peak flops is 312 TFLOPS
+        flops_promised = 70e12 # RTX 3090 BF16 FP32 accumulate
         mfu = flops_achieved / flops_promised
         return mfu
 

train.py

@@ -28,6 +28,12 @@ from torch.nn.parallel import DistributedDataParallel as DDP
 from torch.distributed import init_process_group, destroy_process_group
 
 from model import GPTConfig, GPT
+import random
+
+seed = 1
+torch.manual_seed(seed)
+random.seed(seed)
+np.random.seed(seed)
 
 # -----------------------------------------------------------------------------
 # default config values designed to train a gpt2 (124M) on OpenWebText
@@ -38,34 +44,49 @@ log_interval = 1
 eval_iters = 200
 eval_only = False # if True, script exits right after the first eval
 always_save_checkpoint = True # if True, always save a checkpoint after each eval
-init_from = 'scratch' # 'scratch' or 'resume' or 'gpt2*'
+init_from = 'resume' # 'scratch' or 'resume' or 'gpt2*'
 # wandb logging
-wandb_log = False # disabled by default
-wandb_project = 'owt'
-wandb_run_name = 'gpt2' # 'run' + str(time.time())
 # data
 dataset = 'openwebtext'
-gradient_accumulation_steps = 5 * 8 # used to simulate larger batch sizes
-batch_size = 12 # if gradient_accumulation_steps > 1, this is the micro-batch size
+
+wandb_log = False
+wandb_project = 'owt'
+wandb_run_name='gpt2'
+
+# these make the total batch size be ~0.5M
+# 12 batch size * 1024 block size * 5 gradaccum * 8 GPUs = 491,520
+batch_size = 8
+block_size = 1024
+gradient_accumulation_steps = 8 * 8
+
+# this makes total number of tokens be 300B
+max_iters = 3000
+lr_decay_iters = 3000
+
+# eval stuff
+eval_interval = 500
+eval_iters = 200
+log_interval = 10
+
+# weight decay
+weight_decay = 1e-1
+
 block_size = 1024
 # model
-n_layer = 12
-n_head = 12
-n_embd = 768
+n_layer = 6
+n_head = 8
+n_embd = 512
 dropout = 0.0 # for pretraining 0 is good, for finetuning try 0.1+
 bias = False # do we use bias inside LayerNorm and Linear layers?
 # adamw optimizer
 learning_rate = 6e-4 # max learning rate
-max_iters = 600000 # total number of training iterations
-weight_decay = 1e-1
 beta1 = 0.9
 beta2 = 0.95
 grad_clip = 1.0 # clip gradients at this value, or disable if == 0.0
 # learning rate decay settings
 decay_lr = True # whether to decay the learning rate
-warmup_iters = 2000 # how many steps to warm up for
-lr_decay_iters = 600000 # should be ~= max_iters per Chinchilla
-min_lr = 6e-5 # minimum learning rate, should be ~= learning_rate/10 per Chinchilla
+warmup_iters = 500 # how many steps to warm up for
+min_lr = 6e-4 # minimum learning rate, should be ~= learning_rate/10 per Chinchilla
 # DDP settings
 backend = 'nccl' # 'nccl', 'gloo', etc.
 # system
@@ -74,7 +95,6 @@ dtype = 'bfloat16' if torch.cuda.is_available() and torch.cuda.is_bf16_supported
 compile = True # use PyTorch 2.0 to compile the model to be faster
 # -----------------------------------------------------------------------------
 config_keys = [k for k,v in globals().items() if not k.startswith('_') and isinstance(v, (int, float, bool, str))]
-exec(open('configurator.py').read()) # overrides from command line or config file
 config = {k: globals()[k] for k in config_keys} # will be useful for logging
 # -----------------------------------------------------------------------------
 
@@ -103,7 +123,6 @@ print(f"tokens per iteration will be: {tokens_per_iter:,}")
 
 if master_process:
     os.makedirs(out_dir, exist_ok=True)
-torch.manual_seed(1337 + seed_offset)
 torch.backends.cuda.matmul.allow_tf32 = True # allow tf32 on matmul
 torch.backends.cudnn.allow_tf32 = True # allow tf32 on cudnn
 device_type = 'cuda' if 'cuda' in device else 'cpu' # for later use in torch.autocast
@@ -112,15 +131,16 @@ ptdtype = {'float32': torch.float32, 'bfloat16': torch.bfloat16, 'float16': torc
 ctx = nullcontext() if device_type == 'cpu' else torch.amp.autocast(device_type=device_type, dtype=ptdtype)
 
 # poor man's data loader
-data_dir = os.path.join('data', dataset)
-def get_batch(split):
+data_dir = "."
+def get_batch(split, step):
     # We recreate np.memmap every batch to avoid a memory leak, as per
     # https://stackoverflow.com/questions/45132940/numpy-memmap-memory-usage-want-to-iterate-once/61472122#61472122
     if split == 'train':
         data = np.memmap(os.path.join(data_dir, 'train.bin'), dtype=np.uint16, mode='r')
     else:
         data = np.memmap(os.path.join(data_dir, 'val.bin'), dtype=np.uint16, mode='r')
-    ix = torch.randint(len(data) - block_size, (batch_size,))
+    d_rng = random.Random(f"{split}-{step}-{seed}")
+    ix = [ d_rng.randint(0, len(data) - block_size) for _ in range(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])
     if device_type == 'cuda':
@@ -158,7 +178,7 @@ if init_from == 'scratch':
 elif init_from == 'resume':
     print(f"Resuming training from {out_dir}")
     # resume training from a checkpoint.
-    ckpt_path = os.path.join(out_dir, 'ckpt.pt')
+    ckpt_path = os.path.join(out_dir, 'ckpt1500.pt')
     checkpoint = torch.load(ckpt_path, map_location=device)
     checkpoint_model_args = checkpoint['model_args']
     # force these config attributes to be equal otherwise we can't even resume training
@@ -213,13 +233,13 @@ if ddp:
 
 # helps estimate an arbitrarily accurate loss over either split using many batches
 @torch.no_grad()
-def estimate_loss():
+def estimate_loss(step):
     out = {}
     model.eval()
     for split in ['train', 'val']:
         losses = torch.zeros(eval_iters)
         for k in range(eval_iters):
-            X, Y = get_batch(split)
+            X, Y = get_batch(split, step)
             with ctx:
                 logits, loss = model(X, Y)
             losses[k] = loss.item()
@@ -247,9 +267,9 @@ if wandb_log and master_process:
     wandb.init(project=wandb_project, name=wandb_run_name, config=config)
 
 # training loop
-X, Y = get_batch('train') # fetch the very first batch
-t0 = time.time()
+X, Y = get_batch('train', f"{iter_num}-{0}") # fetch the very first batch
 local_iter_num = 0 # number of iterations in the lifetime of this process
+t0 = time.time()
 raw_model = model.module if ddp else model # unwrap DDP container if needed
 running_mfu = -1.0
 while True:
@@ -261,7 +281,7 @@ while True:
 
     # evaluate the loss on train/val sets and write checkpoints
     if iter_num % eval_interval == 0 and master_process:
-        losses = estimate_loss()
+        losses = estimate_loss(iter_num)
         print(f"step {iter_num}: train loss {losses['train']:.4f}, val loss {losses['val']:.4f}")
         if wandb_log:
             wandb.log({
@@ -273,7 +293,6 @@ while True:
             })
         if losses['val'] < best_val_loss or always_save_checkpoint:
             best_val_loss = losses['val']
-            if iter_num > 0:
             checkpoint = {
                 'model': raw_model.state_dict(),
                 'optimizer': optimizer.state_dict(),
@@ -283,7 +302,7 @@ while True:
                 'config': config,
             }
             print(f"saving checkpoint to {out_dir}")
-                torch.save(checkpoint, os.path.join(out_dir, 'ckpt.pt'))
+            torch.save(checkpoint, os.path.join(out_dir, f'ckpt{iter_num}.pt'))
     if iter_num == 0 and eval_only:
         break
 
@@ -300,7 +319,7 @@ while True:
             logits, loss = model(X, Y)
             loss = loss / gradient_accumulation_steps # scale the loss to account for gradient accumulation
         # immediately async prefetch next batch while model is doing the forward pass on the GPU
-        X, Y = get_batch('train')
+        X, Y = get_batch('train', f"{iter_num}-{micro_step + 1}")
         # backward pass, with gradient scaling if training in fp16
         scaler.scale(loss).backward()
     # clip the gradient