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import os
import time
import math
import pickle
import inspect
import json
from contextlib import nullcontext
from dataclasses import dataclass
import numpy as np
import torch
import torch.nn as nn
from torch.nn import functional as F
import argparse
# --- BEGIN model.py ---
class LayerNorm(nn.Module):
"""LayerNorm but with an optional bias. PyTorch doesn't support simply bias=False"""
def __init__(self, ndim, bias):
super().__init__()
self.weight = nn.Parameter(torch.ones(ndim))
self.bias = nn.Parameter(torch.zeros(ndim)) if bias else None
def forward(self, input):
return F.layer_norm(input, self.weight.shape, self.weight, self.bias, 1e-5)
class CausalSelfAttention(nn.Module):
def __init__(self, config):
super().__init__()
assert config.n_embd % config.n_head == 0
# key, query, value projections for all heads, but in a batch
self.c_attn = nn.Linear(config.n_embd, 3 * config.n_embd, bias=config.bias)
# output projection
self.c_proj = nn.Linear(config.n_embd, config.n_embd, bias=config.bias)
# regularization
self.attn_dropout = nn.Dropout(config.dropout)
self.resid_dropout = nn.Dropout(config.dropout)
self.n_head = config.n_head
self.n_embd = config.n_embd
self.dropout = config.dropout
# flash attention make GPU go brrrrr but support is only in PyTorch >= 2.0
self.flash = hasattr(torch.nn.functional, "scaled_dot_product_attention")
if not self.flash:
print(
"WARNING: using slow attention. Flash Attention requires PyTorch >= 2.0"
)
# causal mask to ensure that attention is only applied to the left in the input sequence
self.register_buffer(
"bias",
torch.tril(torch.ones(config.block_size, config.block_size)).view(
1, 1, config.block_size, config.block_size
),
)
def forward(self, x):
B, T, C = (
x.size()
) # batch size, sequence length, embedding dimensionality (n_embd)
# calculate query, key, values for all heads in batch and move head forward to be the batch dim
q, k, v = self.c_attn(x).split(self.n_embd, dim=2)
k = k.view(B, T, self.n_head, C // self.n_head).transpose(
1, 2
) # (B, nh, T, hs)
q = q.view(B, T, self.n_head, C // self.n_head).transpose(
1, 2
) # (B, nh, T, hs)
v = v.view(B, T, self.n_head, C // self.n_head).transpose(
1, 2
) # (B, nh, T, hs)
# causal self-attention; Self-attend: (B, nh, T, hs) x (B, nh, hs, T) -> (B, nh, T, T)
if self.flash:
# efficient attention using Flash Attention CUDA kernels
y = torch.nn.functional.scaled_dot_product_attention(
q,
k,
v,
attn_mask=None,
dropout_p=self.dropout if self.training else 0,
is_causal=True,
)
else:
# manual implementation of attention
att = (q @ k.transpose(-2, -1)) * (1.0 / math.sqrt(k.size(-1)))
att = att.masked_fill(self.bias[:, :, :T, :T] == 0, float("-inf"))
att = F.softmax(att, dim=-1)
att = self.attn_dropout(att)
y = att @ v # (B, nh, T, T) x (B, nh, T, hs) -> (B, nh, T, hs)
y = (
y.transpose(1, 2).contiguous().view(B, T, C)
) # re-assemble all head outputs side by side
# output projection
y = self.resid_dropout(self.c_proj(y))
return y
class MLP(nn.Module):
def __init__(self, config):
super().__init__()
self.c_fc = nn.Linear(config.n_embd, 4 * config.n_embd, bias=config.bias)
self.gelu = nn.GELU()
self.c_proj = nn.Linear(4 * config.n_embd, config.n_embd, bias=config.bias)
self.dropout = nn.Dropout(config.dropout)
def forward(self, x):
x = self.c_fc(x)
x = self.gelu(x)
x = self.c_proj(x)
x = self.dropout(x)
return x
class Block(nn.Module):
def __init__(self, config):
super().__init__()
self.ln_1 = LayerNorm(config.n_embd, bias=config.bias)
self.attn = CausalSelfAttention(config)
self.ln_2 = LayerNorm(config.n_embd, bias=config.bias)
self.mlp = MLP(config)
def forward(self, x):
x = x + self.attn(self.ln_1(x))
x = x + self.mlp(self.ln_2(x))
return x
@dataclass
class GPTConfig:
block_size: int = 1024
vocab_size: int = (
50304 # GPT-2 vocab_size of 50257, padded up to nearest multiple of 64 for efficiency
)
n_layer: int = 12
n_head: int = 12
n_embd: int = 768
dropout: float = 0.0
bias: bool = (
True # True: bias in Linears and LayerNorms, like GPT-2. False: a bit better and faster
)
class GPT(nn.Module):
def __init__(self, config):
super().__init__()
assert config.vocab_size is not None
assert config.block_size is not None
self.config = config
self.transformer = nn.ModuleDict(
dict(
wte=nn.Embedding(config.vocab_size, config.n_embd),
wpe=nn.Embedding(config.block_size, config.n_embd),
drop=nn.Dropout(config.dropout),
h=nn.ModuleList([Block(config) for _ in range(config.n_layer)]),
ln_f=LayerNorm(config.n_embd, bias=config.bias),
)
)
self.lm_head = nn.Linear(config.n_embd, config.vocab_size, bias=False)
# with weight tying when using torch.compile() some warnings get generated:
# "UserWarning: functional_call was passed multiple values for tied weights.
# This behavior is deprecated and will be an error in future versions"
# not 100% sure what this is, so far seems to be harmless. TODO investigate
self.transformer.wte.weight = (
self.lm_head.weight
) # https://paperswithcode.com/method/weight-tying
# init all weights
self.apply(self._init_weights)
# apply special scaled init to the residual projections, per GPT-2 paper
for pn, p in self.named_parameters():
if pn.endswith("c_proj.weight"):
torch.nn.init.normal_(
p, mean=0.0, std=0.02 / math.sqrt(2 * config.n_layer)
)
# report number of parameters
print("number of parameters: %.2fM" % (self.get_num_params() / 1e6,))
def get_num_params(self, non_embedding=True):
"""
Return the number of parameters in the model.
For non-embedding count (default), the position embeddings get subtracted.
The token embeddings would too, except due to the parameter sharing these
params are actually used as weights in the final layer, so we include them.
"""
n_params = sum(p.numel() for p in self.parameters())
if non_embedding:
n_params -= self.transformer.wpe.weight.numel()
return n_params
def _init_weights(self, module):
if isinstance(module, nn.Linear):
torch.nn.init.normal_(module.weight, mean=0.0, std=0.02)
if module.bias is not None:
torch.nn.init.zeros_(module.bias)
elif isinstance(module, nn.Embedding):
torch.nn.init.normal_(module.weight, mean=0.0, std=0.02)
def forward(self, idx, targets=None):
device = idx.device
b, t = idx.size()
assert (
t <= self.config.block_size
), f"Cannot forward sequence of length {t}, block size is only {self.config.block_size}"
pos = torch.arange(0, t, dtype=torch.long, device=device) # shape (t)
# forward the GPT model itself
tok_emb = self.transformer.wte(idx) # token embeddings of shape (b, t, n_embd)
pos_emb = self.transformer.wpe(pos) # position embeddings of shape (t, n_embd)
x = self.transformer.drop(tok_emb + pos_emb)
for block in self.transformer.h:
x = block(x)
x = self.transformer.ln_f(x)
if targets is not None:
# if we are given some desired targets also calculate the loss
logits = self.lm_head(x)
loss = F.cross_entropy(
logits.view(-1, logits.size(-1)), targets.view(-1), ignore_index=-1
)
else:
# inference-time mini-optimization: only forward the lm_head on the very last position
logits = self.lm_head(
x[:, [-1], :]
) # note: using list [-1] to preserve the time dim
loss = None
return logits, loss
def crop_block_size(self, block_size):
# model surgery to decrease the block size if necessary
# e.g. we may load the GPT2 pretrained model checkpoint (block size 1024)
# but want to use a smaller block size for some smaller, simpler model
assert block_size <= self.config.block_size
self.config.block_size = block_size
self.transformer.wpe.weight = nn.Parameter(
self.transformer.wpe.weight[:block_size]
)
for block in self.transformer.h:
if hasattr(block.attn, "bias"):
block.attn.bias = block.attn.bias[:, :, :block_size, :block_size]
def configure_optimizers(self, weight_decay, learning_rate, betas, device_type):
# start with all of the candidate parameters
param_dict = {pn: p for pn, p in self.named_parameters()}
# filter out those that do not require grad
param_dict = {pn: p for pn, p in param_dict.items() if p.requires_grad}
# create optim groups. Any parameters that is 2D will be weight decayed, otherwise no.
# i.e. all weight tensors in matmuls + embeddings decay, all biases and layernorms don't.
decay_params = [p for n, p in param_dict.items() if p.dim() >= 2]
nodecay_params = [p for n, p in param_dict.items() if p.dim() < 2]
optim_groups = [
{"params": decay_params, "weight_decay": weight_decay},
{"params": nodecay_params, "weight_decay": 0.0},
]
num_decay_params = sum(p.numel() for p in decay_params)
num_nodecay_params = sum(p.numel() for p in nodecay_params)
print(
f"num decayed parameter tensors: {len(decay_params)}, with {num_decay_params:,} parameters"
)
print(
f"num non-decayed parameter tensors: {len(nodecay_params)}, with {num_nodecay_params:,} parameters"
)
# Create AdamW optimizer and use the fused version if it is available
fused_available = "fused" in inspect.signature(torch.optim.AdamW).parameters
use_fused = fused_available and device_type == "cuda"
extra_args = dict(fused=True) if use_fused else dict()
optimizer = torch.optim.AdamW(
optim_groups, lr=learning_rate, betas=betas, **extra_args
)
print(f"using fused AdamW: {use_fused}")
return optimizer
@torch.no_grad()
def generate(self, idx, max_new_tokens, temperature=1.0, top_k=None):
"""
Take a conditioning sequence of indices idx (LongTensor of shape (b,t)) and complete
the sequence max_new_tokens times, feeding the predictions back into the model each time.
Most likely you'll want to make sure to be in model.eval() mode of operation for this.
"""
for _ in range(max_new_tokens):
# if the sequence context is growing too long we must crop it at block_size
idx_cond = (
idx
if idx.size(1) <= self.config.block_size
else idx[:, -self.config.block_size :]
)
# forward the model to get the logits for the index in the sequence
logits, _ = self(idx_cond)
# pluck the logits at the final step and scale by desired temperature
logits = logits[:, -1, :] / temperature
# optionally crop the logits to only the top k options
if top_k is not None:
v, _ = torch.topk(logits, min(top_k, logits.size(-1)))
logits[logits < v[:, [-1]]] = -float("Inf")
# apply softmax to convert logits to (normalized) probabilities
probs = F.softmax(logits, dim=-1)
# sample from the distribution
idx_next = torch.multinomial(probs, num_samples=1)
# append sampled index to the running sequence and continue
idx = torch.cat((idx, idx_next), dim=1)
return idx
# --- END model.py ---
def train(dataset="shakespeare_char", out_dir="run_0", seed_offset=0):
# -----------------------------------------------------------------------------
# default config values designed to train a gpt2 (124M) on OpenWebText
# data
gradient_accumulation_steps = 1
batch_size = 64 if dataset == "shakespeare_char" else 32
block_size = 256 # context of up to 256 previous characters
# I/O
eval_interval = 250 if dataset == "shakespeare_char" else 1000
log_interval = 10 if dataset == "shakespeare_char" else 100
eval_iters = 200
eval_only = False # if True, script exits right after the first eval
always_save_checkpoint = False # we expect to overfit on this small dataset, so only save when val improves
never_save_checkpoint = True # never save checkpoints
# model
n_layer = 6 # baby GPT model :)
n_head = 6
n_embd = 384
dropout = 0.2 # 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 = 1e-3 if dataset == "shakespeare_char" else 5e-4
max_iters = 5000 if dataset == "shakespeare_char" else 100000
weight_decay = 1e-1
beta1 = 0.9
beta2 = 0.99 # make a bit bigger because number of tokens per iter is small
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 = 100 if dataset == "shakespeare_char" else 200
lr_decay_iters = max_iters # make equal to max_iters usually
min_lr = 1e-4 if dataset == "shakespeare_char" else 5e-5
# DDP settings
backend = "nccl" # 'nccl', 'gloo', etc.
# system
device = "cuda" # Always use CUDA
dtype = (
"bfloat16"
if torch.cuda.is_available() and torch.cuda.is_bf16_supported()
else "float16"
) # 'float32', 'bfloat16', or 'float16', the latter will auto implement a GradScaler
compile = True # do not torch compile the model on macbooks
# various inits, derived attributes, I/O setup
# if not ddp, we are running on a single gpu, and one process
master_process = True
tokens_per_iter = gradient_accumulation_steps * batch_size * block_size
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
# note: float16 data type will automatically use a GradScaler
ptdtype = {
"float32": torch.float32,
"bfloat16": torch.bfloat16,
"float16": torch.float16,
}[dtype]
ctx = (
nullcontext()
if device_type == "cpu"
else torch.amp.autocast(device_type=device_type, dtype=ptdtype)
)
# poor man's data loader
# ?theres some error in the ../.. file classifier, certainly use the absolute path for data directory_
if out_dir == "run_0":
data_dir = os.path.join("/home/fdpp28/sakana/AI-Scientist/data", dataset)
else:
data_dir = os.path.join("/home/fdpp28/sakana/AI-Scientist/data", dataset)
def get_batch(split):
# 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,))
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":
# pin arrays x,y, which allows us to move them to GPU asynchronously (non_blocking=True)
x, y = x.pin_memory().to(device, non_blocking=True), y.pin_memory().to(
device, non_blocking=True
)
else:
x, y = x.to(device), y.to(device)
return x, y
iter_num = 0
best_val_loss = 1e9
# attempt to derive vocab_size from the dataset
meta_path = os.path.join(data_dir, "meta.pkl")
meta_vocab_size = None
if os.path.exists(meta_path):
with open(meta_path, "rb") as f:
meta = pickle.load(f)
meta_vocab_size = meta["vocab_size"]
print(f"found vocab_size = {meta_vocab_size} (inside {meta_path})")
# model init
model_args = dict(
n_layer=n_layer,
n_head=n_head,
n_embd=n_embd,
block_size=block_size,
bias=bias,
vocab_size=None,
dropout=dropout,
) # start with model_args from command line
# init a new model from scratch
print("Initializing a new model from scratch")
# determine the vocab size we'll use for from-scratch training
if meta_vocab_size is None:
print(
"defaulting to vocab_size of GPT-2 to 50304 (50257 rounded up for efficiency)"
)
model_args["vocab_size"] = meta_vocab_size if meta_vocab_size is not None else 50304
gptconf = GPTConfig(**model_args)
model = GPT(gptconf)
# crop down the model block size if desired, using model surgery
if block_size < model.config.block_size:
model.crop_block_size(block_size)
model_args["block_size"] = (
block_size # so that the checkpoint will have the right value
)
model.to(device)
# initialize a GradScaler. If enabled=False scaler is a no-op
scaler = torch.cuda.amp.GradScaler(enabled=(dtype == "float16"))
# optimizer
optimizer = model.configure_optimizers(
weight_decay, learning_rate, (beta1, beta2), device_type
)
checkpoint = None # free up memory
# compile the model
if compile:
print("compiling the model... (takes a ~minute)")
unoptimized_model = model
model = torch.compile(model) # requires PyTorch 2.0
# helps estimate an arbitrarily accurate loss over either split using many batches
@torch.no_grad()
def estimate_loss():
out = {}
model.eval()
for split in ["train", "val"]:
losses = torch.zeros(eval_iters)
for k in range(eval_iters):
X, Y = get_batch(split)
with ctx:
logits, loss = model(X, Y)
losses[k] = loss.item()
out[split] = losses.mean()
model.train()
return out
# learning rate decay scheduler (cosine with warmup)
def get_lr(it):
# 1) linear warmup for warmup_iters steps
if it < warmup_iters:
return learning_rate * it / warmup_iters
# 2) if it > lr_decay_iters, return min learning rate
if it > lr_decay_iters:
return min_lr
# 3) in between, use cosine decay down to min learning rate
decay_ratio = (it - warmup_iters) / (lr_decay_iters - warmup_iters)
assert 0 <= decay_ratio <= 1
coeff = 0.5 * (1.0 + math.cos(math.pi * decay_ratio)) # coeff ranges 0..1
return min_lr + coeff * (learning_rate - min_lr)
# logging
val_log_info = []
train_log_info = []
# training loop
X, Y = get_batch("train") # fetch the very first batch
og_t0 = time.time()
t0 = time.time()
local_iter_num = 0 # number of iterations in the lifetime of this process
raw_model = model
while True:
# determine and set the learning rate for this iteration
lr = get_lr(iter_num) if decay_lr else learning_rate
for param_group in optimizer.param_groups:
param_group["lr"] = lr
# evaluate the loss on train/val sets and write checkpoints
if iter_num % eval_interval == 0 and master_process:
losses = estimate_loss()
print(
f"step {iter_num}: train loss {losses['train']:.4f}, val loss {losses['val']:.4f}"
)
val_log_info.append(
{
"iter": iter_num,
"train/loss": losses["train"].item(),
"val/loss": losses["val"].item(),
"lr": lr,
}
)
if losses["val"] < best_val_loss or always_save_checkpoint:
best_val_loss = losses["val"]
if iter_num > 0 and not never_save_checkpoint:
checkpoint = {
"model": raw_model.state_dict(),
"optimizer": optimizer.state_dict(),
"model_args": model_args,
"iter_num": iter_num,
"best_val_loss": best_val_loss,
}
print(f"saving checkpoint to {out_dir}")
torch.save(checkpoint, os.path.join(out_dir, "ckpt.pt"))
if iter_num == 0 and eval_only:
break
# forward backward update, with optional gradient accumulation to simulate larger batch size
# and using the GradScaler if data type is float16
for micro_step in range(gradient_accumulation_steps):
with ctx:
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")
# backward pass, with gradient scaling if training in fp16
scaler.scale(loss).backward()
# clip the gradient
if grad_clip != 0.0:
scaler.unscale_(optimizer)
torch.nn.utils.clip_grad_norm_(model.parameters(), grad_clip)
# step the optimizer and scaler if training in fp16
scaler.step(optimizer)
scaler.update()
# flush the gradients as soon as we can, no need for this memory anymore
optimizer.zero_grad(set_to_none=True)
# timing and logging
t1 = time.time()
dt = t1 - t0
t0 = t1
if iter_num % log_interval == 0 and master_process:
# get loss as float. note: this is a CPU-GPU sync point
# scale up to undo the division above, approximating the true total loss (exact would have been a sum)
lossf = loss.item() * gradient_accumulation_steps
print(f"iter {iter_num}: loss {lossf:.4f}, time {dt*1000:.2f}ms")
train_log_info.append(
{
"iter": iter_num,
"loss": lossf,
"time": dt * 1000,
}
)
iter_num += 1
local_iter_num += 1
# termination conditions
if iter_num > max_iters:
break
print("training done")
print(f"Best validation loss: {best_val_loss}")
print(f"Total train time: {(time.time() - og_t0) / 60:.2f} mins")
final_info = {
"final_train_loss": lossf,
"best_val_loss": best_val_loss.item(),
"total_train_time": time.time() - og_t0,
}
# === SAMPLING SCRIPT ===
# New parameters for generation
start = " "
num_samples = 10 # number of samples to draw
max_new_tokens = 500 # number of tokens generated in each sample
temperature = (
0.8 # 1.0 = no change, < 1.0 = less random, > 1.0 = more random, in predictions
)
top_k = 200 # retain only the top_k most likely tokens, clamp others to have 0 probability
# Encoding setup
assert os.path.exists(
meta_path
), "meta.pkl not found, please run training script first"
print(f"Loading meta from {meta_path}...")
with open(meta_path, "rb") as f:
meta = pickle.load(f)
stoi, itos = meta["stoi"], meta["itos"]
encode = lambda s: [stoi[c] for c in s]
decode = lambda l: "".join([itos[i] for i in l])
# Encode the beginning of the prompt
if start.startswith("FILE:"):
with open(start[5:], "r", encoding="utf-8") as f:
start = f.read()
start_ids = encode(start)
x = torch.tensor(start_ids, dtype=torch.long, device=device)[None, ...]
# Run generation
model.eval()
results = []
with torch.no_grad():
with ctx:
for k in range(num_samples):
start_time = time.time()
y = model.generate(
x, max_new_tokens, temperature=temperature, top_k=top_k
)
end_time = time.time()
generated_text = decode(y[0].tolist())
inference_time = end_time - start_time
tokens_per_second = max_new_tokens / inference_time
print(f"Sample {k+1}:")
print(generated_text)
print(f"Inference time: {inference_time:.2f} seconds")
print(f"Tokens per second: {tokens_per_second:.2f}")
print("---------------")
results.append(
{
"sample_id": k + 1,
"generated_text": generated_text,
"inference_time": inference_time,
"tokens_per_second": tokens_per_second,
}
)
# Calculate and print average inference speed
avg_tokens_per_second = sum(r["tokens_per_second"] for r in results) / len(results)
print(f"Average tokens per second: {avg_tokens_per_second:.2f}")
final_info["avg_inference_tokens_per_second"] = avg_tokens_per_second
with open(
os.path.join(out_dir, f"final_info_{dataset}_{seed_offset}.json"), "w"
) as f:
json.dump(final_info, f)
return final_info, train_log_info, val_log_info
parser = argparse.ArgumentParser(description="Run experiment")
parser.add_argument("--out_dir", type=str, default="run_0", help="Output directory")
args = parser.parse_args()
if __name__ == "__main__":
num_seeds = {
"shakespeare_char": 3,
"enwik8": 1,
"text8": 1,
}
out_dir = args.out_dir
all_results = {}
final_infos = {}
for dataset in ["shakespeare_char", "enwik8", "text8"]:
final_info_list = []
for seed_offset in range(num_seeds[dataset]):
final_info, train_info, val_info = train(dataset, out_dir, seed_offset)
all_results[f"{dataset}_{seed_offset}_final_info"] = final_info
all_results[f"{dataset}_{seed_offset}_train_info"] = train_info
all_results[f"{dataset}_{seed_offset}_val_info"] = val_info
final_info_list.append(final_info)
final_info_dict = {
k: [d[k] for d in final_info_list] for k in final_info_list[0].keys()
}
means = {f"{k}_mean": np.mean(v) for k, v in final_info_dict.items()}
stderrs = {
f"{k}_stderr": np.std(v) / len(v) for k, v in final_info_dict.items()
}
final_infos[dataset] = {
"means": means,
"stderrs": stderrs,
"final_info_dict": final_info_dict,
}
with open(os.path.join(out_dir, "final_info.json"), "w") as f:
json.dump(final_infos, f)
with open(os.path.join(out_dir, "all_results.npy"), "wb") as f:
np.save(f, all_results)