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app.py

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+import os
+import pickle
+from contextlib import nullcontext
+import torch
+import tiktoken
+from model import GPTConfig, GPT
+import gradio as gr
+
+def nanogpt(start:str , max_new_tokens = 500, num_samples =2):
+
+
+  # -----------------------------------------------------------------------------
+  init_from = 'resume' # either 'resume' (from an out_dir) or a gpt2 variant (e.g. 'gpt2-xl')
+  out_dir = 'out-shakespeare-char' # ignored if init_from is not 'resume'
+  #start = "God is great. I love Him." #"\n"  or "<|endoftext|>" or etc. Can also specify a file, use as: "FILE:prompt.txt"
+  #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
+  seed = 1337
+  device = 'cpu' # examples: 'cpu', 'cuda', 'cuda:0', 'cuda:1', etc.
+  dtype = 'bfloat16' if torch.cuda.is_available() and torch.cuda.is_bf16_supported() else 'float16' # 'float32' or 'bfloat16' or 'float16'
+  compile = False # use PyTorch 2.0 to compile the model to be faster
+  #exec(open('configurator.py').read()) # overrides from command line or config file
+  # -----------------------------------------------------------------------------
+
+  torch.manual_seed(seed)
+  torch.cuda.manual_seed(seed)
+  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
+  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)
+
+  # model
+  if init_from == 'resume':
+      # init from a model saved in a specific directory
+      ckpt_path = 'ckpt.pt'
+      checkpoint = torch.load(ckpt_path, map_location=device)
+      gptconf = GPTConfig(**checkpoint['model_args'])
+      model = GPT(gptconf)
+      state_dict = checkpoint['model']
+      unwanted_prefix = '_orig_mod.'
+      for k,v in list(state_dict.items()):
+          if k.startswith(unwanted_prefix):
+              state_dict[k[len(unwanted_prefix):]] = state_dict.pop(k)
+      model.load_state_dict(state_dict)
+  
+
+  model.eval()
+  model.to(device)
+  if compile:
+      model = torch.compile(model) # requires PyTorch 2.0 (optional)
+
+  # look for the meta pickle in case it is available in the dataset folder
+  load_meta = False
+  if init_from == 'resume' and 'config' in checkpoint and 'dataset' in checkpoint['config']: # older checkpoints might not have these...
+      meta_path = os.path.join('data', checkpoint['config']['dataset'], 'meta.pkl')
+      load_meta = os.path.exists(meta_path)
+  if load_meta:
+      print(f"Loading meta from {meta_path}...")
+      with open(meta_path, 'rb') as f:
+          meta = pickle.load(f)
+      # TODO want to make this more general to arbitrary encoder/decoder schemes
+      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])
+  else:
+      # ok let's assume gpt-2 encodings by default
+      print("No meta.pkl found, assuming GPT-2 encodings...")
+      enc = tiktoken.get_encoding("gpt2")
+      encode = lambda s: enc.encode(s, allowed_special={"<|endoftext|>"})
+      decode = lambda l: enc.decode(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
+  with torch.no_grad():
+      with ctx:
+          
+              y = model.generate(x, max_new_tokens, temperature=temperature, top_k=top_k)
+              #print(decode(y[0].tolist()))
+              output = decode(y[0].tolist())
+  return output
+
+INTERFACE = gr.Interface(fn=nanogpt, inputs=[gr.Textbox(label= "Prompt"),gr.Slider(300,500, "number", label= "Maximum number of tokens to be geenrated")] , outputs=gr.Text(label= "Generated Text"), title="NanoGPT",
+                 description="NanoGPT is a large transformer-based language model with 10.65 million parameters, trained on a small dataset of Shakespeare work (size: 1MB only). It is trained with character level tokeniation with a simple objective: predict the next char, given all of the previous chars within some text.",
+                 examples = [['We as the new generation AI enginners.',300,1],
+                ['A forgotten era of humility and happiness',300,2],
+                
+           ]).launch(debug=True)

bench.py

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+"""
+A much shorter version of train.py for benchmarking
+"""
+import os
+from contextlib import nullcontext
+import numpy as np
+import time
+import torch
+from model import GPTConfig, GPT
+
+# -----------------------------------------------------------------------------
+batch_size = 12
+block_size = 1024
+bias = False
+real_data = True
+seed = 1337
+device = 'cuda' # examples: 'cpu', 'cuda', 'cuda:0', 'cuda:1', etc.
+dtype = 'bfloat16' if torch.cuda.is_available() and torch.cuda.is_bf16_supported() else 'float16' # 'float32' or 'bfloat16' or 'float16'
+compile = True # use PyTorch 2.0 to compile the model to be faster
+profile = False # use pytorch profiler, or just simple benchmarking?
+exec(open('configurator.py').read()) # overrides from command line or config file
+# -----------------------------------------------------------------------------
+
+torch.manual_seed(seed)
+torch.cuda.manual_seed(seed)
+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
+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)
+
+# data loading init
+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.pin_memory().to(device, non_blocking=True), y.pin_memory().to(device, non_blocking=True)
+        return x, y
+else:
+    # alternatively, if fixed data is desired to not care about data loading
+    x = torch.randint(50304, (batch_size, block_size), device=device)
+    y = torch.randint(50304, (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
+    dropout = 0, # for determinism
+    bias = bias,
+)
+model = GPT(gptconf)
+model.to(device)
+
+optimizer = model.configure_optimizers(weight_decay=1e-2, learning_rate=1e-4, betas=(0.9, 0.95), device_type=device_type)
+
+if compile:
+    print("Compiling model...")
+    model = torch.compile(model) # pytorch 2.0
+
+if profile:
+    # useful docs on pytorch profiler:
+    # - tutorial https://pytorch.org/tutorials/intermediate/tensorboard_profiler_tutorial.html
+    # - api https://pytorch.org/docs/stable/profiler.html#torch.profiler.profile
+    wait, warmup, active = 5, 5, 5
+    num_steps = wait + warmup + active
+    with torch.profiler.profile(
+        activities=[torch.profiler.ProfilerActivity.CPU, torch.profiler.ProfilerActivity.CUDA],
+        schedule=torch.profiler.schedule(wait=wait, warmup=warmup, active=active, repeat=1),
+        on_trace_ready=torch.profiler.tensorboard_trace_handler('./bench_log'),
+        record_shapes=False,
+        profile_memory=False,
+        with_stack=False, # incurs an additional overhead, disable if not needed
+        with_flops=True,
+        with_modules=False, # only for torchscript models atm
+    ) as prof:
+
+        X, Y = get_batch('train')
+        for k in range(num_steps):
+            with ctx:
+                logits, loss = model(X, Y)
+            X, Y = get_batch('train')
+            optimizer.zero_grad(set_to_none=True)
+            loss.backward()
+            optimizer.step()
+            lossf = loss.item()
+            print(f"{k}/{num_steps} loss: {lossf:.4f}")
+
+            prof.step() # notify the profiler at end of each step
+
+else:
+
+    # simple benchmarking
+    torch.cuda.synchronize()
+    for stage, num_steps in enumerate([10, 20]): # burnin, then benchmark
+        t0 = time.time()
+        X, Y = get_batch('train')
+        for k in range(num_steps):
+            with ctx:
+                logits, loss = model(X, Y)
+            X, Y = get_batch('train')
+            optimizer.zero_grad(set_to_none=True)
+            loss.backward()
+            optimizer.step()
+            lossf = loss.item()
+            print(f"{k}/{num_steps} loss: {lossf:.4f}")
+        torch.cuda.synchronize()
+        t1 = time.time()
+        dt = t1-t0
+        mfu = model.estimate_mfu(batch_size * 1 * num_steps, dt)
+        if stage == 1:
+            print(f"time per iteration: {dt/num_steps*1000:.4f}ms, MFU: {mfu*100:.2f}%")

ckpt.pt

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+version https://git-lfs.github.com/spec/v1
+oid sha256:5febb604b592cb5d24feded2e47b649d8e33dbba8e3b1b493302b9b5f6702507
+size 128985109

configurator.py

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+"""
+Poor Man's Configurator. Probably a terrible idea. Example usage:
+$ python train.py config/override_file.py --batch_size=32
+this will first run config/override_file.py, then override batch_size to 32
+
+The code in this file will be run as follows from e.g. train.py:
+>>> exec(open('configurator.py').read())
+
+So it's not a Python module, it's just shuttling this code away from train.py
+The code in this script then overrides the globals()
+
+I know people are not going to love this, I just really dislike configuration
+complexity and having to prepend config. to every single variable. If someone
+comes up with a better simple Python solution I am all ears.
+"""
+
+import sys
+from ast import literal_eval
+
+for arg in sys.argv[1:]:
+    if '=' not in arg:
+        # assume it's the name of a config file
+        assert not arg.startswith('--')
+        config_file = arg
+        print(f"Overriding config with {config_file}:")
+        with open(config_file) as f:
+            print(f.read())
+        exec(open(config_file).read())
+    else:
+        # assume it's a --key=value argument
+        assert arg.startswith('--')
+        key, val = arg.split('=')
+        key = key[2:]
+        if key in globals():
+            try:
+                # attempt to eval it it (e.g. if bool, number, or etc)
+                attempt = literal_eval(val)
+            except (SyntaxError, ValueError):
+                # if that goes wrong, just use the string
+                attempt = val
+            # ensure the types match ok
+            assert type(attempt) == type(globals()[key])
+            # cross fingers
+            print(f"Overriding: {key} = {attempt}")
+            globals()[key] = attempt
+        else:
+            raise ValueError(f"Unknown config key: {key}")

model.py

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+"""
+Full definition of a GPT Language Model, all of it in this single file.
+References:
+1) the official GPT-2 TensorFlow implementation released by OpenAI:
+https://github.com/openai/gpt-2/blob/master/src/model.py
+2) huggingface/transformers PyTorch implementation:
+https://github.com/huggingface/transformers/blob/main/src/transformers/models/gpt2/modeling_gpt2.py
+"""
+
+import math
+import inspect
+from dataclasses import dataclass
+
+import torch
+import torch.nn as nn
+from torch.nn import functional as F
+
+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]
+
+    @classmethod
+    def from_pretrained(cls, model_type, override_args=None):
+        assert model_type in {'gpt2', 'gpt2-medium', 'gpt2-large', 'gpt2-xl'}
+        override_args = override_args or {} # default to empty dict
+        # only dropout can be overridden see more notes below
+        assert all(k == 'dropout' for k in override_args)
+        from transformers import GPT2LMHeadModel
+        print("loading weights from pretrained gpt: %s" % model_type)
+
+        # n_layer, n_head and n_embd are determined from model_type
+        config_args = {
+            'gpt2':         dict(n_layer=12, n_head=12, n_embd=768),  # 124M params
+            'gpt2-medium':  dict(n_layer=24, n_head=16, n_embd=1024), # 350M params
+            'gpt2-large':   dict(n_layer=36, n_head=20, n_embd=1280), # 774M params
+            'gpt2-xl':      dict(n_layer=48, n_head=25, n_embd=1600), # 1558M params
+        }[model_type]
+        print("forcing vocab_size=50257, block_size=1024, bias=True")
+        config_args['vocab_size'] = 50257 # always 50257 for GPT model checkpoints
+        config_args['block_size'] = 1024 # always 1024 for GPT model checkpoints
+        config_args['bias'] = True # always True for GPT model checkpoints
+        # we can override the dropout rate, if desired
+        if 'dropout' in override_args:
+            print(f"overriding dropout rate to {override_args['dropout']}")
+            config_args['dropout'] = override_args['dropout']
+        # create a from-scratch initialized minGPT model
+        config = GPTConfig(**config_args)
+        model = GPT(config)
+        sd = model.state_dict()
+        sd_keys = sd.keys()
+        sd_keys = [k for k in sd_keys if not k.endswith('.attn.bias')] # discard this mask / buffer, not a param
+
+        # init a huggingface/transformers model
+        model_hf = GPT2LMHeadModel.from_pretrained(model_type)
+        sd_hf = model_hf.state_dict()
+
+        # copy while ensuring all of the parameters are aligned and match in names and shapes
+        sd_keys_hf = sd_hf.keys()
+        sd_keys_hf = [k for k in sd_keys_hf if not k.endswith('.attn.masked_bias')] # ignore these, just a buffer
+        sd_keys_hf = [k for k in sd_keys_hf if not k.endswith('.attn.bias')] # same, just the mask (buffer)
+        transposed = ['attn.c_attn.weight', 'attn.c_proj.weight', 'mlp.c_fc.weight', 'mlp.c_proj.weight']
+        # basically the openai checkpoints use a "Conv1D" module, but we only want to use a vanilla Linear
+        # this means that we have to transpose these weights when we import them
+        assert len(sd_keys_hf) == len(sd_keys), f"mismatched keys: {len(sd_keys_hf)} != {len(sd_keys)}"
+        for k in sd_keys_hf:
+            if any(k.endswith(w) for w in transposed):
+                # special treatment for the Conv1D weights we need to transpose
+                assert sd_hf[k].shape[::-1] == sd[k].shape
+                with torch.no_grad():
+                    sd[k].copy_(sd_hf[k].t())
+            else:
+                # vanilla copy over the other parameters
+                assert sd_hf[k].shape == sd[k].shape
+                with torch.no_grad():
+                    sd[k].copy_(sd_hf[k])
+
+        return model
+
+    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
+
+    def estimate_mfu(self, fwdbwd_per_iter, dt):
+        """ estimate model flops utilization (MFU) in units of A100 bfloat16 peak FLOPS """
+        # first estimate the number of flops we do per iteration.
+        # see PaLM paper Appendix B as ref: https://arxiv.org/abs/2204.02311
+        N = self.get_num_params()
+        cfg = self.config
+        L, H, Q, T = cfg.n_layer, cfg.n_head, cfg.n_embd//cfg.n_head, cfg.block_size
+        flops_per_token = 6*N + 12*L*H*Q*T
+        flops_per_fwdbwd = flops_per_token * T
+        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
+        mfu = flops_achieved / flops_promised
+        return mfu
+
+    @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

sample.py

@@ -0,0 +1,89 @@
+"""
+Sample from a trained model
+"""
+import os
+import pickle
+from contextlib import nullcontext
+import torch
+import tiktoken
+from model import GPTConfig, GPT
+
+# -----------------------------------------------------------------------------
+init_from = 'resume' # either 'resume' (from an out_dir) or a gpt2 variant (e.g. 'gpt2-xl')
+out_dir = 'out' # ignored if init_from is not 'resume'
+start = "\n" # or "<|endoftext|>" or etc. Can also specify a file, use as: "FILE:prompt.txt"
+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
+seed = 1337
+device = 'cuda' # examples: 'cpu', 'cuda', 'cuda:0', 'cuda:1', etc.
+dtype = 'bfloat16' if torch.cuda.is_available() and torch.cuda.is_bf16_supported() else 'float16' # 'float32' or 'bfloat16' or 'float16'
+compile = False # use PyTorch 2.0 to compile the model to be faster
+exec(open('configurator.py').read()) # overrides from command line or config file
+# -----------------------------------------------------------------------------
+
+torch.manual_seed(seed)
+torch.cuda.manual_seed(seed)
+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
+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)
+
+# model
+if init_from == 'resume':
+    # init from a model saved in a specific directory
+    ckpt_path = os.path.join(out_dir, 'ckpt.pt')
+    checkpoint = torch.load(ckpt_path, map_location=device)
+    gptconf = GPTConfig(**checkpoint['model_args'])
+    model = GPT(gptconf)
+    state_dict = checkpoint['model']
+    unwanted_prefix = '_orig_mod.'
+    for k,v in list(state_dict.items()):
+        if k.startswith(unwanted_prefix):
+            state_dict[k[len(unwanted_prefix):]] = state_dict.pop(k)
+    model.load_state_dict(state_dict)
+elif init_from.startswith('gpt2'):
+    # init from a given GPT-2 model
+    model = GPT.from_pretrained(init_from, dict(dropout=0.0))
+
+model.eval()
+model.to(device)
+if compile:
+    model = torch.compile(model) # requires PyTorch 2.0 (optional)
+
+# look for the meta pickle in case it is available in the dataset folder
+load_meta = False
+if init_from == 'resume' and 'config' in checkpoint and 'dataset' in checkpoint['config']: # older checkpoints might not have these...
+    meta_path = os.path.join('data', checkpoint['config']['dataset'], 'meta.pkl')
+    load_meta = os.path.exists(meta_path)
+if load_meta:
+    print(f"Loading meta from {meta_path}...")
+    with open(meta_path, 'rb') as f:
+        meta = pickle.load(f)
+    # TODO want to make this more general to arbitrary encoder/decoder schemes
+    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])
+else:
+    # ok let's assume gpt-2 encodings by default
+    print("No meta.pkl found, assuming GPT-2 encodings...")
+    enc = tiktoken.get_encoding("gpt2")
+    encode = lambda s: enc.encode(s, allowed_special={"<|endoftext|>"})
+    decode = lambda l: enc.decode(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
+with torch.no_grad():
+    with ctx:
+        for k in range(num_samples):
+            y = model.generate(x, max_new_tokens, temperature=temperature, top_k=top_k)
+            print(decode(y[0].tolist()))
+            print('---------------')