diff --git a/quantized_model.py b/quantized_model.py new file mode 100644 index 000000000..76a86a71f --- /dev/null +++ b/quantized_model.py @@ -0,0 +1,264 @@ +import torch +import torch.nn as nn +from torch.nn import functional as F + +from model import GPTConfig, GPT +import math +import os + +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 + self.quant = torch.quantization.QuantStub() + # 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 + self.dequant = torch.quantization.DeQuantStub() + # 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) + x = self.quant(x) + # 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 + k,q,v = self.dequant(k),self.dequant(q),self.dequant(v) + 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) + y = self.quant(y) + 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)) + y = self.quant(y) + return y + +class MLP(nn.Module): + + def __init__(self, config): + super().__init__() + self.quant = torch.quantization.QuantStub() + 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) + self.dequant = torch.quantization.DeQuantStub() + + def forward(self, x): + x = self.quant(x) + x = self.c_fc(x) + x = self.gelu(x) + x = self.c_proj(x) + x = self.dropout(x) + x = self.dequant(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 + +class QuantGPT(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) + self.transformer.wte.weight = self.lm_head.weight + + self.apply(self._init_weights) + 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)) + + 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) + + tok_emb = self.transformer.wte(idx) + pos_emb = self.transformer.wpe(pos) + 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: + logits = self.lm_head(x) + loss = F.cross_entropy(logits.view(-1, logits.size(-1)), targets.view(-1), ignore_index=-1) + else: + logits = self.lm_head(x[:, [-1], :]) # note: using list [-1] to preserve the time dim + loss = None + + return logits, loss + + @classmethod + def from_pretrained(cls, model_type, override_args=None): + assert model_type in {'gpt2', 'gpt2-medium', 'gpt2-large', 'gpt2-xl'} + from transformers import GPT2LMHeadModel + + config_args = { + 'gpt2': dict(n_layer=12, n_head=12, n_embd=768), + 'gpt2-medium': dict(n_layer=24, n_head=16, n_embd=1024), + 'gpt2-large': dict(n_layer=36, n_head=20, n_embd=1280), + 'gpt2-xl': dict(n_layer=48, n_head=25, n_embd=1600), + }[model_type] + + config_args['vocab_size'] = 50257 + config_args['block_size'] = 1024 + config_args['bias'] = True + + if override_args: + config_args.update(override_args) + + config = GPTConfig(**config_args) + quant_model = QuantGPT(config) + sd = quant_model.state_dict() + sd_keys = sd.keys() + sd_keys = [k for k in sd_keys if not k.endswith('.attn.bias')] + + model_hf = GPT2LMHeadModel.from_pretrained(model_type) + sd_hf = model_hf.state_dict() + + sd_keys_hf = sd_hf.keys() + sd_keys_hf = [k for k in sd_keys_hf if not k.endswith('.attn.masked_bias')] + sd_keys_hf = [k for k in sd_keys_hf if not k.endswith('.attn.bias')] + transposed = ['attn.c_attn.weight', 'attn.c_proj.weight', 'mlp.c_fc.weight', 'mlp.c_proj.weight'] + + 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): + assert sd_hf[k].shape[::-1] == sd[k].shape + with torch.no_grad(): + sd[k].copy_(sd_hf[k].t()) + else: + assert sd_hf[k].shape == sd[k].shape + with torch.no_grad(): + sd[k].copy_(sd_hf[k]) + + # NOTE: if you use the cuda use the "fbgemm" and if mac M1/M2 or mobile use the qnnpack + torch.backends.quantized.engine = 'qnnpack' + quant_model.qconfig = torch.quantization.get_default_qconfig("qnnpack") + quant_model.transformer.wte.qconfig = torch.ao.quantization.float_qparams_weight_only_qconfig + quant_model.transformer.wpe.qconfig = torch.ao.quantization.float_qparams_weight_only_qconfig + + torch.quantization.prepare(quant_model, inplace=True) + + sample_inp = torch.randint(0, config.vocab_size, (1, config.block_size)) + quant_model(sample_inp) + + torch.quantization.convert(quant_model, inplace=True) + + return quant_model + + 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) + + #same as the gpt model + @torch.no_grad() + def generate(self, idx, max_new_tokens, temperature=1.0, top_k=None): + 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 + +if __name__ == "__main__": + def model_size(model: nn.Module, name:str): + torch.save(model.state_dict(), "temp_model.p") + size_kb = os.path.getsize("temp_model.p")/1e3 + os.remove("temp_model.p") + + print(f"\n Model: {name} -- Model Size: {size_kb:.2f} KB") + return size_kb + + gpt2_config = GPTConfig() + gpt_2 = GPT.from_pretrained('gpt2') + gpt_2_size = model_size(gpt_2, 'GPT2') + + q_gpt_2 = QuantGPT.from_pretrained('gpt2') + q_gpt_2_size = model_size(q_gpt_2, 'QGPT2') + + print(f"\nDiffrence -- {gpt_2_size - q_gpt_2_size:.2f} KB") + \ No newline at end of file