chore: import upstream snapshot with attribution
This commit is contained in:
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"""
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---
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title: Receptance Weighted Key Value (RWKV)
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summary: >
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This implements the RWKV model
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using PyTorch with explanations.
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---
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# Receptance Weighted Key Value (RWKV)
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This is a tutorial/implementation of RWKV
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from paper [RWKV: Reinventing RNNs for the Transformer Era](https://arxiv.org/pdf/2305.13048.pdf)
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in [PyTorch](https://pytorch.org/).
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Full definition of a RWKV Language Model, all of it in this single file.
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References:
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1) [the official RWKV PyTorch implementation released by Bo Peng](https://github.com/BlinkDL/RWKV-LM/blob/main/RWKV-v4neo/src/model.py)
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2) [huggingface/transformers PyTorch implementation](https://github.com/huggingface/transformers/blob/main/src/transformers/models/rwkv/modeling_rwkv.py)
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"""
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import torch
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import torch.nn as nn
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from torch.nn import functional as F
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PREV_X_TIME = 0
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NUM_STATE = 1
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DEN_STATE = 2
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MAX_STATE = 3
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PREV_X_CHANNEL = 4
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class LayerNorm(nn.Module):
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"""
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### Layer normalization with bias
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"""
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def __init__(self, ndim, bias):
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super().__init__()
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self.weight = nn.Parameter(torch.ones(ndim))
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self.bias = nn.Parameter(torch.zeros(ndim)) if bias else None
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def forward(self, input):
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return F.layer_norm(input, self.weight.shape, self.weight, self.bias, 1e-5)
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class L2Wrap(torch.autograd.Function):
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"""
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### L2 loss wrapper
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[ref](https://github.com/BlinkDL/RWKV-LM/blob/cca1b5e8e597cf40675882bb10b46287c844e35c/RWKV-v4/src/model.py#L21)
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"""
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@staticmethod
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def forward(ctx, loss, y):
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ctx.save_for_backward(y)
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return loss
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@staticmethod
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def backward(ctx, grad_output):
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y = ctx.saved_tensors[0]
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# to encourage the logits to be close to 0
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factor = 1e-4 / (y.shape[0] * y.shape[1])
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maxx, ids = torch.max(y, -1, keepdim=True)
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gy = torch.zeros_like(y)
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gy.scatter_(-1, ids, maxx * factor)
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return grad_output, gy
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class ChannelMixing(nn.Module):
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"""
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### Channel Mixing
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"""
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def __init__(self, config, layer_id):
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super().__init__()
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self.time_shift = nn.ZeroPad2d((0, 0, 1, -1))
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# token shifting
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self.layer_id = layer_id
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n_embd = config.n_embd
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intermediate_size = (
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config.intermediate_size if config.intermediate_size is not None else 4 * n_embd
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)
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# Learnable Matrix
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self.key_proj = nn.Linear(n_embd, intermediate_size, bias=False)
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self.value_proj = nn.Linear(intermediate_size, n_embd, bias=False)
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self.receptance_proj = nn.Linear(n_embd, n_embd, bias=False)
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# Learnable Vector
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self.time_mix_key = nn.Parameter(torch.empty(1, 1, n_embd))
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self.time_mix_receptance = nn.Parameter(torch.empty(1, 1, n_embd))
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def forward(self, x, state=None):
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"""
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# x = (Batch,Time,Channel)
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"""
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if state is not None:
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prev_x = state[self.layer_id, :, [PREV_X_CHANNEL], :]
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state[self.layer_id, :, [PREV_X_CHANNEL], :] = x
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else:
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prev_x = self.time_shift(x)
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# $r_t=W_r \cdot (\mu_r x_t + (1-\mu_r)x_{t-1})$
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receptance = x * self.time_mix_receptance + prev_x * (1 - self.time_mix_receptance)
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receptance = self.receptance_proj(receptance)
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# $k_t=W_k \cdot (\mu_k x_t + (1-\mu_k)x_{t-1})$
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key = x * self.time_mix_key + prev_x * (1 - self.time_mix_key)
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key = self.key_proj(key)
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# $V_t=W_v \cdot max(k_t,0)^2$
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value = self.value_proj(torch.square(torch.relu(key)))
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# $o_t=\sigma(r_t) \odot v_t$
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out = F.sigmoid(receptance) * value
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return out, state
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class TimeMixing(nn.Module):
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"""
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### Time Mixing
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"""
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def __init__(self, config, layer_id):
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super().__init__()
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self.config = config
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self.time_shift = nn.ZeroPad2d((0, 0, 1, -1))
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self.layer_id = layer_id
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n_embd = config.n_embd
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attn_sz = n_embd
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# learnable matrix
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self.key_proj = nn.Linear(n_embd, attn_sz, bias=False)
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self.value_proj = nn.Linear(n_embd, attn_sz, bias=False)
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self.receptance_proj = nn.Linear(n_embd, attn_sz, bias=False)
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self.output_proj = nn.Linear(attn_sz, n_embd, bias=False)
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# learnable vector
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self.time_decay = nn.Parameter(torch.empty(attn_sz))
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self.time_first = nn.Parameter(torch.empty(attn_sz))
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self.time_mix_key = nn.Parameter(torch.empty(1, 1, n_embd))
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self.time_mix_value = nn.Parameter(torch.empty(1, 1, n_embd))
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self.time_mix_receptance = nn.Parameter(torch.empty(1, 1, n_embd))
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def forward(self, x, state=None):
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"""
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x = (Batch,Time,Channel)
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"""
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if state is not None:
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prev_x = state[self.layer_id, :, [PREV_X_TIME], :]
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state[self.layer_id, :, [PREV_X_TIME], :] = x
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else:
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prev_x = self.time_shift(x)
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# $r_t=W_r \cdot (\mu_r x_t + (1-\mu_r)x_{t-1})$
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receptance = x * self.time_mix_receptance + prev_x * (1 - self.time_mix_receptance)
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receptance = self.receptance_proj(receptance)
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# $k_t=W_k \cdot (\mu_k x_t + (1-\mu_k)x_{t-1})$
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key = x * self.time_mix_key + prev_x * (1 - self.time_mix_key)
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key = self.key_proj(key)
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# $v_t=W_v \cdot (\mu_v x_t + (1-\mu_v)x_{t-1})$
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value = x * self.time_mix_value + prev_x * (1 - self.time_mix_value)
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value = self.value_proj(value)
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# WKV calculation
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_, seq_length, _ = key.size()
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output = torch.zeros_like(key)
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if state is None:
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num_state = torch.zeros_like(key[:, 0], dtype=torch.float32)
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den_state = torch.zeros_like(key[:, 0], dtype=torch.float32)
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max_state = torch.zeros_like(key[:, 0], dtype=torch.float32) - 1e38
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else:
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num_state = state[self.layer_id, :, NUM_STATE, :]
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den_state = state[self.layer_id, :, DEN_STATE, :]
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max_state = state[self.layer_id, :, MAX_STATE, :]
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time_decay = -torch.exp(self.time_decay)
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for current_index in range(seq_length):
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current_key = key[:, current_index].float()
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current_value = value[:, current_index]
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# $wkv_t=\frac{\sum^{t-1}_{i=1}d^{-(t-1-i)w+k_i}v_i+e^{u+k_t}v_t}{\sum^{t-1}_{i=1}e^{-(t-1-i)w+k_i}+e^{u+k_t}}$
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max_for_output = torch.maximum(max_state, current_key + self.time_first)
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e1 = torch.exp(max_state - max_for_output)
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e2 = torch.exp(current_key + self.time_first - max_for_output)
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numerator = e1 * num_state + e2 * current_value
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denominator = e1 * den_state + e2
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output[:, current_index] = (numerator / denominator).to(output.dtype)
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# Update state for next iteration
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max_for_state = torch.maximum(max_state + time_decay, current_key)
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e1 = torch.exp(max_state + time_decay - max_for_state)
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e2 = torch.exp(current_key - max_for_state)
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num_state = e1 * num_state + e2 * current_value
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den_state = e1 * den_state + e2
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max_state = max_for_state
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# update states
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state[self.layer_id, :, NUM_STATE, :] = num_state
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state[self.layer_id, :, DEN_STATE, :] = den_state
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state[self.layer_id, :, MAX_STATE, :] = max_state
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wkv, state = self.wkv_function(key, value, use_customized_cuda_kernel=self.config.use_customized_cuda_kernel,
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state=state)
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# $o_t=W_o \cdot (\sigma(r_t) \odot wkv_t)$
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rwkv = F.sigmoid(receptance) * wkv
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rwkv = self.output_proj(rwkv)
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return rwkv, state
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class Block(nn.Module):
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"""
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## RWKV block element
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"""
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def __init__(self, config, layer_id):
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super().__init__()
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self.ln_1 = LayerNorm(config.n_embd, bias=config.bias)
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self.attn = TimeMixing(config, layer_id)
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self.ln_2 = LayerNorm(config.n_embd, bias=config.bias)
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self.ffn = ChannelMixing(config, layer_id)
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def forward(self, x, state=None):
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# state: [batch_size, 5 , n_embd]
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# time mixing
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residual = x
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x, state = self.attn(self.ln_1(x), state=state)
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x = x + residual
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# channel mixing
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residual = x
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x, state = self.ffn(self.ln_2(x), state=state)
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x = x + residual
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return x, state
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class RWKV(nn.Module):
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"""
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## RWKV
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"""
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def __init__(self, config, lr_init=0.0008):
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super().__init__()
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assert config.vocab_size is not None
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assert config.block_size is not None
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self.config = config
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self.lr_init = lr_init ## used to initialize embedding parameters
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self.n_layer = config.n_layer
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self.n_embd = config.n_embd
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# Initiate model layers
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self.rwkv = nn.ModuleDict(dict(
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wte=nn.Embedding(config.vocab_size, config.n_embd),
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ln_p=LayerNorm(config.n_embd, bias=config.bias),
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h=nn.ModuleList([Block(config, layer_id) for layer_id in range(config.n_layer)]),
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ln_f=LayerNorm(config.n_embd, bias=config.bias),
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))
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# Output linear layer
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self.lm_head = nn.Linear(config.n_embd, config.vocab_size, bias=False)
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def forward(self, idx, targets=None, state=None, return_state=False):
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b, t = idx.size()
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assert t <= self.config.block_size, f"Cannot forward sequence of length {t}, block size is only {self.config.block_size}"
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# Embedding Layer
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x = self.rwkv.wte(idx)
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# Layer Norm
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x = self.rwkv.ln_p(x)
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# RWKV Blocks
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for block_idx, block in enumerate(self.rwkv.h):
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x, state = block(x, state)
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x = self.rwkv.ln_f(x)
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# Logit Layer and loss Function (for training)
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if targets is not None:
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# if we are given some desired targets also calculate the loss
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logits = self.lm_head(x)
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loss = F.cross_entropy(logits.view(-1, logits.size(-1)), targets.view(-1), ignore_index=-1)
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if self.training:
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loss = L2Wrap.apply(loss, logits)
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else:
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# inference-time mini-optimization: only forward the lm_head on the very last position
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logits = self.lm_head(x[:, [-1], :]) # note: using list [-1] to preserve the time dim
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loss = None
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# Return Logits and loss
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if return_state:
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return logits, loss, state
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else:
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return logits, loss
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@@ -0,0 +1,24 @@
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from labml.configs import BaseConfigs
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class RWKVConfigs(BaseConfigs):
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"""
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## Transformer Configurations
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This defines configurations for a transformer.
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The configurations are calculate using option functions.
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These are lazy loaded and therefore only the necessary modules
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are calculated.
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"""
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# Number of attention heads
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n_heads: int = 8
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# Transformer embedding size
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d_model: int = 512
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# Number of layers
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n_layers: int = 6
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# Dropout probability
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dropout: float = 0.1
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# Number of tokens in the source vocabulary (for token embeddings)
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n_src_vocab: int
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# Number of tokens in the target vocabulary (to generate logits for prediction)
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n_tgt_vocab: int
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@@ -0,0 +1,169 @@
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import inspect
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import math
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import torch
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import torch.nn as nn
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from labml_nn.rwkv.configs import RWKVConfigs
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from labml_nn.rwkv import RWKV
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from labml_nn.rwkv import TimeMixing
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from labml import experiment
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from labml.configs import option
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from labml_nn.experiments.nlp_autoregression import NLPAutoRegressionConfigs
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class Configs(NLPAutoRegressionConfigs):
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"""
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## Configurations
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This inherits from
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[`NLPAutoRegressionConfigs`](../../experiments/nlp_autoregression.html#NLPAutoRegressionConfigs)
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"""
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# RWKV model
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model: RWKV
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rwkv: RWKVConfigs
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# number of warmup iterations
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warmup_iters: int = 2000
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# total number of training iterations
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max_iters: int = 600000
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# weight decay
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weight_decay: float = 1e-1
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# Custom optimizer
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beta1: float = 0.9
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beta2: float = 0.95
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optimizer = 'rwkv_optimizer'
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@option(Configs.rwkv, 'RWKV')
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def _rwkv_configs(c: Configs):
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"""
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### RWKV configurations
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"""
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# We use our
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# [configurable RWKV implementation](../configs.html#RWKVConfigs)
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conf = RWKVConfigs()
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# Set the vocabulary sizes for embeddings and generating logits
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conf.n_src_vocab = c.n_tokens
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conf.n_tgt_vocab = c.n_tokens
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return conf
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def _init_weights(module, rwkv: RWKVConfigs):
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# initialize Vector Parameters in TimeMixing
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if isinstance(module, TimeMixing):
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layer_id = module.layer_id
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n_layer = module.n_layer
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n_embd = module.n_embd
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attn_sz = n_embd
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with torch.no_grad():
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ratio_0_to_1 = layer_id / (n_layer - 1) # 0 to 1
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ratio_1_to_almost0 = 1.0 - (layer_id / n_layer) # 1 to ~0
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ddd = torch.ones(1, 1, n_embd)
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for i in range(n_embd):
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ddd[0, 0, i] = i / n_embd
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decay_speed = torch.ones(attn_sz)
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for h in range(attn_sz):
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decay_speed[h] = -5 + 8 * (h / (attn_sz - 1)) ** (0.7 + 1.3 * ratio_0_to_1)
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module.time_decay = nn.Parameter(decay_speed)
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zigzag = torch.tensor([(i + 1) % 3 - 1 for i in range(attn_sz)]) * 0.5
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module.time_first = nn.Parameter(torch.ones(attn_sz) * math.log(0.3) + zigzag)
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module.time_mix_key = nn.Parameter(torch.pow(ddd, ratio_1_to_almost0))
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module.time_mix_value = nn.Parameter(torch.pow(ddd, ratio_1_to_almost0) + 0.3 * ratio_0_to_1)
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module.time_mix_receptance = nn.Parameter(torch.pow(ddd, 0.5 * ratio_1_to_almost0))
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@option(Configs.model)
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def _model(c: Configs):
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"""
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Create RWKV model and initialize weights
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"""
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m = RWKV(c.rwkv).to(c.device)
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# Apply custom weight initialization
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m.apply(_init_weights, c.rwkv)
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return m
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@option(NLPAutoRegressionConfigs.optimizer)
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def _configure_optimizers(c: NLPAutoRegressionConfigs):
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# start with all of the candidate parameters
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param_dict = {pn: p for pn, p in c.model.named_parameters()}
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# filter out those that do not require grad
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param_dict = {pn: p for pn, p in param_dict.items() if p.requires_grad}
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# create optim groups. Any parameters that is 2D will be weight decayed, otherwise no.
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# i.e. all weight tensors in matmuls + embeddings decay, all biases and layernorms don't.
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decay_params = [p for n, p in param_dict.items() if p.dim() >= 2]
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nodecay_params = [p for n, p in param_dict.items() if p.dim() < 2]
|
||||
optim_groups = [
|
||||
{'params': decay_params, 'weight_decay': c.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 c.device_type == 'cuda'
|
||||
extra_args = dict(fused=True) if use_fused else dict()
|
||||
optimizer = torch.optim.AdamW(optim_groups, lr=c.learning_rate, betas=c.betas, **extra_args)
|
||||
print(f"using fused AdamW: {use_fused}")
|
||||
|
||||
return optimizer
|
||||
|
||||
|
||||
def main():
|
||||
# Create experiment
|
||||
experiment.create(name="RWKV")
|
||||
# Create configs
|
||||
conf = Configs()
|
||||
print(conf.model)
|
||||
# Override configurations
|
||||
experiment.configs(conf, {
|
||||
# Use character level tokenizer
|
||||
'tokenizer': 'character',
|
||||
# Prompt separator is blank
|
||||
'prompt_separator': '',
|
||||
# Starting prompt for sampling
|
||||
'prompt': 'It is ',
|
||||
# Use Tiny Shakespeare dataset
|
||||
'text': 'tiny_shakespeare',
|
||||
|
||||
# Use a context size of $128$
|
||||
'seq_len': 128,
|
||||
# Train for $32$ epochs
|
||||
'epochs': 32,
|
||||
# Batch size $128$
|
||||
'batch_size': 128,
|
||||
# Switch between training and validation for $10$ times
|
||||
# per epoch
|
||||
'inner_iterations': 10,
|
||||
|
||||
'rwkv.block_size': 1024,
|
||||
# model
|
||||
'rwkv.n_layer': 12,
|
||||
'rwkv.n_heads': 12,
|
||||
'rwkv.n_embd': 768
|
||||
})
|
||||
|
||||
print(conf.model)
|
||||
# Set models for saving and loading
|
||||
experiment.add_pytorch_models({'model': conf.model})
|
||||
|
||||
# Start the experiment
|
||||
with experiment.start():
|
||||
# Run training
|
||||
conf.run()
|
||||
|
||||
|
||||
#
|
||||
if __name__ == '__main__':
|
||||
main()
|
||||
Reference in New Issue
Block a user