mirror of
https://github.com/rasbt/LLMs-from-scratch.git
synced 2025-11-03 19:30:26 +00:00
820 lines
30 KiB
Plaintext
820 lines
30 KiB
Plaintext
{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {
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"id": "Dlv8N4uWtXcN"
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},
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"source": [
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"<table style=\"width:100%\">\n",
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"<tr>\n",
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"<td style=\"vertical-align:middle; text-align:left;\">\n",
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"<font size=\"2\">\n",
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"Supplementary code for the <a href=\"http://mng.bz/orYv\">Build a Large Language Model From Scratch</a> book by <a href=\"https://sebastianraschka.com\">Sebastian Raschka</a><br>\n",
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"<br>Code repository: <a href=\"https://github.com/rasbt/LLMs-from-scratch\">https://github.com/rasbt/LLMs-from-scratch</a>\n",
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"</font>\n",
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"</td>\n",
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"<td style=\"vertical-align:middle; text-align:left;\">\n",
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"<a href=\"http://mng.bz/orYv\"><img src=\"https://sebastianraschka.com/images/LLMs-from-scratch-images/cover-small.webp\" width=\"100px\"></a>\n",
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"</td>\n",
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"</tr>\n",
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"</table>"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"id": "V6BXGeEJ_s-8"
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},
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"source": [
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"# Understanding PyTorch Buffers"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"id": "aQt9Ob1Y_8EH"
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},
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"source": [
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"In essence, PyTorch buffers are tensor attributes associated with a PyTorch module or model similar to parameters, but unlike parameters, buffers are not updated during training.\n",
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"\n",
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"Buffers in PyTorch are particularly useful when dealing with GPU computations, as they need to be transferred between devices (like from CPU to GPU) alongside the model's parameters. Unlike parameters, buffers do not require gradient computation, but they still need to be on the correct device to ensure that all computations are performed correctly.\n",
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"\n",
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"In chapter 3, we use PyTorch buffers via `self.register_buffer`, which is only briefly explained in the book. Since the concept and purpose are not immediately clear, this code notebook offers a longer explanation with a hands-on example."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"id": "dAwGo_gYLY45"
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},
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"source": [
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"## An example without buffers"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"id": "0qBQC9IPAJVZ"
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},
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"source": [
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"Suppose we have the following code, which is based on code from chapter 3. This version has been modified to exclude buffers. It implements the causal self-attention mechanism used in LLMs:"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 1,
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"metadata": {
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"id": "7wx-_rokAN04"
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},
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"outputs": [],
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"source": [
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"import torch\n",
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"import torch.nn as nn\n",
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"\n",
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"class CausalAttentionWithoutBuffers(nn.Module):\n",
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"\n",
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" def __init__(self, d_in, d_out, context_length,\n",
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" dropout, qkv_bias=False):\n",
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" super().__init__()\n",
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" self.d_out = d_out\n",
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" self.W_query = nn.Linear(d_in, d_out, bias=qkv_bias)\n",
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" self.W_key = nn.Linear(d_in, d_out, bias=qkv_bias)\n",
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" self.W_value = nn.Linear(d_in, d_out, bias=qkv_bias)\n",
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" self.dropout = nn.Dropout(dropout)\n",
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" self.mask = torch.triu(torch.ones(context_length, context_length), diagonal=1)\n",
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"\n",
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" def forward(self, x):\n",
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" b, num_tokens, d_in = x.shape\n",
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" keys = self.W_key(x)\n",
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" queries = self.W_query(x)\n",
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" values = self.W_value(x)\n",
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"\n",
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" attn_scores = queries @ keys.transpose(1, 2)\n",
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" attn_scores.masked_fill_(\n",
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" self.mask.bool()[:num_tokens, :num_tokens], -torch.inf)\n",
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" attn_weights = torch.softmax(\n",
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" attn_scores / keys.shape[-1]**0.5, dim=-1\n",
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" )\n",
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" attn_weights = self.dropout(attn_weights)\n",
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"\n",
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" context_vec = attn_weights @ values\n",
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" return context_vec"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"id": "nNrK-wLaNSi7"
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},
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"source": [
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"We can initialize and run the module as follows on some example data:"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 2,
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"metadata": {
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"colab": {
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"base_uri": "https://localhost:8080/"
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},
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"id": "e1MZiIsPA0Py",
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"outputId": "ce1407c6-c082-4755-b8ad-d9adcc9f153a"
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},
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"outputs": [
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{
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"output_type": "stream",
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"name": "stdout",
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"text": [
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"tensor([[[-0.4519, 0.2216],\n",
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" [-0.5874, 0.0058],\n",
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" [-0.6300, -0.0632],\n",
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" [-0.5675, -0.0843],\n",
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" [-0.5526, -0.0981],\n",
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" [-0.5299, -0.1081]],\n",
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"\n",
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" [[-0.4519, 0.2216],\n",
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" [-0.5874, 0.0058],\n",
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" [-0.6300, -0.0632],\n",
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" [-0.5675, -0.0843],\n",
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" [-0.5526, -0.0981],\n",
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" [-0.5299, -0.1081]]])\n"
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]
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}
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],
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"source": [
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"torch.manual_seed(123)\n",
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"\n",
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"inputs = torch.tensor(\n",
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" [[0.43, 0.15, 0.89], # Your (x^1)\n",
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" [0.55, 0.87, 0.66], # journey (x^2)\n",
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" [0.57, 0.85, 0.64], # starts (x^3)\n",
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" [0.22, 0.58, 0.33], # with (x^4)\n",
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" [0.77, 0.25, 0.10], # one (x^5)\n",
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" [0.05, 0.80, 0.55]] # step (x^6)\n",
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")\n",
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"\n",
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"batch = torch.stack((inputs, inputs), dim=0)\n",
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"context_length = batch.shape[1]\n",
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"d_in = inputs.shape[1]\n",
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"d_out = 2\n",
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"\n",
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"ca_without_buffer = CausalAttentionWithoutBuffers(d_in, d_out, context_length, 0.0)\n",
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"\n",
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"with torch.no_grad():\n",
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" context_vecs = ca_without_buffer(batch)\n",
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"\n",
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"print(context_vecs)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"id": "7_hqz6AgCCc1"
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},
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"source": [
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"So far, everything has worked fine so far.\n",
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"\n",
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"However, when training LLMs, we typically use GPUs to accelerate the process. Therefore, let's transfer the `CausalAttentionWithoutBuffers` module onto a GPU device.\n",
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"\n",
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"Please note that this operation requires the code to be run in an environment equipped with GPUs."
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]
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},
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{
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"cell_type": "code",
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"execution_count": 3,
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"metadata": {
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"colab": {
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"base_uri": "https://localhost:8080/"
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},
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"id": "PYwn44HWCPJS",
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"outputId": "d7236e0c-2a43-4770-ccc1-03c9d5d11421"
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},
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"outputs": [
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{
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"output_type": "stream",
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"name": "stdout",
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"text": [
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"Machine has GPU: True\n"
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]
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}
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],
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"source": [
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"print(\"Machine has GPU:\", torch.cuda.is_available())\n",
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"\n",
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"batch = batch.to(\"cuda\")\n",
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"ca_without_buffer.to(\"cuda\");"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"id": "4_lMki2_CoIR"
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},
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"source": [
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"Now, let's run the code again:"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 4,
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"metadata": {
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"colab": {
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"base_uri": "https://localhost:8080/",
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"height": 338
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},
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"id": "KE9iLcjGC1V1",
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"outputId": "ab6921c7-d7dd-44ea-9b92-1911037e3dcc"
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},
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"outputs": [
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{
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"output_type": "error",
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"ename": "RuntimeError",
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"evalue": "expected self and mask to be on the same device, but got mask on cpu and self on cuda:0",
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"traceback": [
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"\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
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"\u001b[0;31mRuntimeError\u001b[0m Traceback (most recent call last)",
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"\u001b[0;32m<ipython-input-4-1e0d2e6638f6>\u001b[0m in \u001b[0;36m<cell line: 1>\u001b[0;34m()\u001b[0m\n\u001b[1;32m 1\u001b[0m \u001b[0;32mwith\u001b[0m \u001b[0mtorch\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mno_grad\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 2\u001b[0;31m \u001b[0mcontext_vecs\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mca_without_buffer\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mbatch\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m 3\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 4\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mcontext_vecs\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0;32m/usr/local/lib/python3.10/dist-packages/torch/nn/modules/module.py\u001b[0m in \u001b[0;36m_wrapped_call_impl\u001b[0;34m(self, *args, **kwargs)\u001b[0m\n\u001b[1;32m 1530\u001b[0m \u001b[0;32mreturn\u001b[0m \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0m_compiled_call_impl\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m*\u001b[0m\u001b[0margs\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m**\u001b[0m\u001b[0mkwargs\u001b[0m\u001b[0;34m)\u001b[0m \u001b[0;31m# type: ignore[misc]\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 1531\u001b[0m \u001b[0;32melse\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m-> 1532\u001b[0;31m \u001b[0;32mreturn\u001b[0m \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0m_call_impl\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m*\u001b[0m\u001b[0margs\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m**\u001b[0m\u001b[0mkwargs\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m 1533\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 1534\u001b[0m \u001b[0;32mdef\u001b[0m \u001b[0m_call_impl\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mself\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m*\u001b[0m\u001b[0margs\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m**\u001b[0m\u001b[0mkwargs\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0;32m/usr/local/lib/python3.10/dist-packages/torch/nn/modules/module.py\u001b[0m in \u001b[0;36m_call_impl\u001b[0;34m(self, *args, **kwargs)\u001b[0m\n\u001b[1;32m 1539\u001b[0m \u001b[0;32mor\u001b[0m \u001b[0m_global_backward_pre_hooks\u001b[0m \u001b[0;32mor\u001b[0m \u001b[0m_global_backward_hooks\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 1540\u001b[0m or _global_forward_hooks or _global_forward_pre_hooks):\n\u001b[0;32m-> 1541\u001b[0;31m \u001b[0;32mreturn\u001b[0m \u001b[0mforward_call\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m*\u001b[0m\u001b[0margs\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m**\u001b[0m\u001b[0mkwargs\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m 1542\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 1543\u001b[0m \u001b[0;32mtry\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0;32m<ipython-input-1-cf1dad0dd611>\u001b[0m in \u001b[0;36mforward\u001b[0;34m(self, x)\u001b[0m\n\u001b[1;32m 21\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 22\u001b[0m \u001b[0mattn_scores\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mqueries\u001b[0m \u001b[0;34m@\u001b[0m \u001b[0mkeys\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mtranspose\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m2\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m---> 23\u001b[0;31m attn_scores.masked_fill_(\n\u001b[0m\u001b[1;32m 24\u001b[0m self.mask.bool()[:num_tokens, :num_tokens], -torch.inf)\n\u001b[1;32m 25\u001b[0m attn_weights = torch.softmax(\n",
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"\u001b[0;31mRuntimeError\u001b[0m: expected self and mask to be on the same device, but got mask on cpu and self on cuda:0"
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]
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}
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],
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"source": [
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"with torch.no_grad():\n",
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" context_vecs = ca_without_buffer(batch)\n",
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"\n",
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"print(context_vecs)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"id": "I7V26PLrC2gk"
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},
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"source": [
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"Running the code resulted in an error. What happened? It seems like we attempted a matrix multiplication between a tensor on a GPU and a tensor on a CPU. But we moved the module to the GPU!?\n",
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"\n",
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"\n",
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"Let's double-check the device locations of some of the tensors:"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 5,
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"metadata": {
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"colab": {
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"base_uri": "https://localhost:8080/"
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},
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"id": "vvYDPBRIDHfU",
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"outputId": "4b9703a8-7035-4a2d-8643-c64d37b7abd2"
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},
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"outputs": [
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{
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"output_type": "stream",
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"name": "stdout",
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"text": [
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"W_query.device: cuda:0\n",
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"mask.device: cpu\n"
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]
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}
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],
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"source": [
|
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"print(\"W_query.device:\", ca_without_buffer.W_query.weight.device)\n",
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"print(\"mask.device:\", ca_without_buffer.mask.device)"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 6,
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"metadata": {
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"colab": {
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"base_uri": "https://localhost:8080/"
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},
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"id": "d11nX-FFOJ3C",
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"outputId": "1e92b0e8-dbc6-41f9-e88f-5d06e0726050"
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},
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"outputs": [
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{
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"output_type": "execute_result",
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"data": {
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"text/plain": [
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"torch.Tensor"
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]
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},
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"metadata": {},
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"execution_count": 6
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}
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],
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"source": [
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"type(ca_without_buffer.mask)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"id": "Ojay-KY-DL5M"
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},
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"source": [
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"As we can see, the `mask` was not moved onto the GPU. That's because it's not a PyTorch parameter like the weights (e.g., `W_query.weight`).\n",
|
|
"\n",
|
|
"This means we have to manually move it to the GPU via `.to(\"cuda\")`:"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"execution_count": 7,
|
|
"metadata": {
|
|
"colab": {
|
|
"base_uri": "https://localhost:8080/"
|
|
},
|
|
"id": "QYirQ63zDYsW",
|
|
"outputId": "304628ac-bc4c-49c2-a0e1-ecf9385ddcd9"
|
|
},
|
|
"outputs": [
|
|
{
|
|
"output_type": "stream",
|
|
"name": "stdout",
|
|
"text": [
|
|
"mask.device: cuda:0\n"
|
|
]
|
|
}
|
|
],
|
|
"source": [
|
|
"ca_without_buffer.mask = ca_without_buffer.mask.to(\"cuda\")\n",
|
|
"print(\"mask.device:\", ca_without_buffer.mask.device)"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"metadata": {
|
|
"id": "4OoTqzkpDfAm"
|
|
},
|
|
"source": [
|
|
"Let's try our code again:"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"execution_count": 8,
|
|
"metadata": {
|
|
"colab": {
|
|
"base_uri": "https://localhost:8080/"
|
|
},
|
|
"id": "WfF0yBZODdAZ",
|
|
"outputId": "291cfb54-86e6-45f9-99d1-fa145319f379"
|
|
},
|
|
"outputs": [
|
|
{
|
|
"output_type": "stream",
|
|
"name": "stdout",
|
|
"text": [
|
|
"tensor([[[-0.4519, 0.2216],\n",
|
|
" [-0.5874, 0.0058],\n",
|
|
" [-0.6300, -0.0632],\n",
|
|
" [-0.5675, -0.0843],\n",
|
|
" [-0.5526, -0.0981],\n",
|
|
" [-0.5299, -0.1081]],\n",
|
|
"\n",
|
|
" [[-0.4519, 0.2216],\n",
|
|
" [-0.5874, 0.0058],\n",
|
|
" [-0.6300, -0.0632],\n",
|
|
" [-0.5675, -0.0843],\n",
|
|
" [-0.5526, -0.0981],\n",
|
|
" [-0.5299, -0.1081]]], device='cuda:0')\n"
|
|
]
|
|
}
|
|
],
|
|
"source": [
|
|
"with torch.no_grad():\n",
|
|
" context_vecs = ca_without_buffer(batch)\n",
|
|
"\n",
|
|
"print(context_vecs)"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"metadata": {
|
|
"id": "oUrVgWuuD7UE"
|
|
},
|
|
"source": [
|
|
"This time, it worked!\n",
|
|
"\n",
|
|
"However, remembering to move individual tensors to the GPU can be tedious. As we will see in the next section, it's easier to use `register_buffer` to register the `mask` as a buffer."
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"metadata": {
|
|
"id": "StS2wUrBLeuW"
|
|
},
|
|
"source": [
|
|
"## An example with buffers"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"metadata": {
|
|
"id": "nEqD2NFzPO6l"
|
|
},
|
|
"source": [
|
|
"Let's now modify the causal attention class to register the causal `mask` as a buffer:"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"execution_count": 9,
|
|
"metadata": {
|
|
"id": "ndsYj3Zf6N8U"
|
|
},
|
|
"outputs": [],
|
|
"source": [
|
|
"import torch\n",
|
|
"import torch.nn as nn\n",
|
|
"\n",
|
|
"class CausalAttentionWithBuffer(nn.Module):\n",
|
|
"\n",
|
|
" def __init__(self, d_in, d_out, context_length,\n",
|
|
" dropout, qkv_bias=False):\n",
|
|
" super().__init__()\n",
|
|
" self.d_out = d_out\n",
|
|
" self.W_query = nn.Linear(d_in, d_out, bias=qkv_bias)\n",
|
|
" self.W_key = nn.Linear(d_in, d_out, bias=qkv_bias)\n",
|
|
" self.W_value = nn.Linear(d_in, d_out, bias=qkv_bias)\n",
|
|
" self.dropout = nn.Dropout(dropout)\n",
|
|
" # Old:\n",
|
|
" # self.mask = torch.triu(torch.ones(context_length, context_length), diagonal=1)\n",
|
|
"\n",
|
|
" # New:\n",
|
|
" self.register_buffer(\"mask\", torch.triu(torch.ones(context_length, context_length), diagonal=1))\n",
|
|
"\n",
|
|
" def forward(self, x):\n",
|
|
" b, num_tokens, d_in = x.shape\n",
|
|
" keys = self.W_key(x)\n",
|
|
" queries = self.W_query(x)\n",
|
|
" values = self.W_value(x)\n",
|
|
"\n",
|
|
" attn_scores = queries @ keys.transpose(1, 2)\n",
|
|
" attn_scores.masked_fill_(\n",
|
|
" self.mask.bool()[:num_tokens, :num_tokens], -torch.inf)\n",
|
|
" attn_weights = torch.softmax(\n",
|
|
" attn_scores / keys.shape[-1]**0.5, dim=-1\n",
|
|
" )\n",
|
|
" attn_weights = self.dropout(attn_weights)\n",
|
|
"\n",
|
|
" context_vec = attn_weights @ values\n",
|
|
" return context_vec"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"metadata": {
|
|
"id": "_AL1X6y3Eb7S"
|
|
},
|
|
"source": [
|
|
"Now, conveniently, if we move the module to the GPU, the mask will be located on the GPU as well:"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"execution_count": 10,
|
|
"metadata": {
|
|
"colab": {
|
|
"base_uri": "https://localhost:8080/"
|
|
},
|
|
"id": "8_VCxEa76j00",
|
|
"outputId": "4d1af501-5a9e-46aa-b1ac-63bf0c68e02a"
|
|
},
|
|
"outputs": [
|
|
{
|
|
"output_type": "stream",
|
|
"name": "stdout",
|
|
"text": [
|
|
"W_query.device: cuda:0\n",
|
|
"mask.device: cuda:0\n"
|
|
]
|
|
}
|
|
],
|
|
"source": [
|
|
"ca_with_buffer = CausalAttentionWithBuffer(d_in, d_out, context_length, 0.0)\n",
|
|
"ca_with_buffer.to(\"cuda\")\n",
|
|
"\n",
|
|
"print(\"W_query.device:\", ca_with_buffer.W_query.weight.device)\n",
|
|
"print(\"mask.device:\", ca_with_buffer.mask.device)"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"execution_count": 11,
|
|
"metadata": {
|
|
"colab": {
|
|
"base_uri": "https://localhost:8080/"
|
|
},
|
|
"id": "TBWvKlMe7bbB",
|
|
"outputId": "e43bf8ab-3fb9-417e-d087-560858332d86"
|
|
},
|
|
"outputs": [
|
|
{
|
|
"output_type": "stream",
|
|
"name": "stdout",
|
|
"text": [
|
|
"tensor([[[0.4772, 0.1063],\n",
|
|
" [0.5891, 0.3257],\n",
|
|
" [0.6202, 0.3860],\n",
|
|
" [0.5478, 0.3589],\n",
|
|
" [0.5321, 0.3428],\n",
|
|
" [0.5077, 0.3493]],\n",
|
|
"\n",
|
|
" [[0.4772, 0.1063],\n",
|
|
" [0.5891, 0.3257],\n",
|
|
" [0.6202, 0.3860],\n",
|
|
" [0.5478, 0.3589],\n",
|
|
" [0.5321, 0.3428],\n",
|
|
" [0.5077, 0.3493]]], device='cuda:0')\n"
|
|
]
|
|
}
|
|
],
|
|
"source": [
|
|
"with torch.no_grad():\n",
|
|
" context_vecs = ca_with_buffer(batch)\n",
|
|
"\n",
|
|
"print(context_vecs)"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"metadata": {
|
|
"id": "xvOTh4NNPjef"
|
|
},
|
|
"source": [
|
|
"As we can see above, registering a tensor as a buffer can make our lives a lot easier: We don't have to remember to move tensors to a target device like a GPU manually."
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"source": [
|
|
"## Buffers and `state_dict`"
|
|
],
|
|
"metadata": {
|
|
"id": "Q-5YYKmJte3h"
|
|
}
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"source": [
|
|
"- Another advantage of PyTorch buffers, over regular tensors, is that they get included in a model's `state_dict`\n",
|
|
"- For example, consider the `state_dict` of the causal attention object without buffers"
|
|
],
|
|
"metadata": {
|
|
"id": "YIHHawPbtjfp"
|
|
}
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"source": [
|
|
"ca_without_buffer.state_dict()"
|
|
],
|
|
"metadata": {
|
|
"colab": {
|
|
"base_uri": "https://localhost:8080/"
|
|
},
|
|
"id": "c217juzqtxsS",
|
|
"outputId": "dbae3c3d-f4f8-4c70-a64f-90906561d8d9"
|
|
},
|
|
"execution_count": 12,
|
|
"outputs": [
|
|
{
|
|
"output_type": "execute_result",
|
|
"data": {
|
|
"text/plain": [
|
|
"OrderedDict([('W_query.weight',\n",
|
|
" tensor([[-0.2354, 0.0191, -0.2867],\n",
|
|
" [ 0.2177, -0.4919, 0.4232]], device='cuda:0')),\n",
|
|
" ('W_key.weight',\n",
|
|
" tensor([[-0.4196, -0.4590, -0.3648],\n",
|
|
" [ 0.2615, -0.2133, 0.2161]], device='cuda:0')),\n",
|
|
" ('W_value.weight',\n",
|
|
" tensor([[-0.4900, -0.3503, -0.2120],\n",
|
|
" [-0.1135, -0.4404, 0.3780]], device='cuda:0'))])"
|
|
]
|
|
},
|
|
"metadata": {},
|
|
"execution_count": 12
|
|
}
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"source": [
|
|
"- The mask is not included in the `state_dict` above\n",
|
|
"- However, the mask *is* included in the `state_dict` below, thanks to registering it as a buffer"
|
|
],
|
|
"metadata": {
|
|
"id": "NdmZuPaqt6aO"
|
|
}
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"source": [
|
|
"ca_with_buffer.state_dict()"
|
|
],
|
|
"metadata": {
|
|
"colab": {
|
|
"base_uri": "https://localhost:8080/"
|
|
},
|
|
"id": "uGIGQAwPt1Pl",
|
|
"outputId": "00f9bc44-63f9-4ebc-87ea-d4b8cafd81c1"
|
|
},
|
|
"execution_count": 13,
|
|
"outputs": [
|
|
{
|
|
"output_type": "execute_result",
|
|
"data": {
|
|
"text/plain": [
|
|
"OrderedDict([('mask',\n",
|
|
" tensor([[0., 1., 1., 1., 1., 1.],\n",
|
|
" [0., 0., 1., 1., 1., 1.],\n",
|
|
" [0., 0., 0., 1., 1., 1.],\n",
|
|
" [0., 0., 0., 0., 1., 1.],\n",
|
|
" [0., 0., 0., 0., 0., 1.],\n",
|
|
" [0., 0., 0., 0., 0., 0.]], device='cuda:0')),\n",
|
|
" ('W_query.weight',\n",
|
|
" tensor([[-0.1362, 0.1853, 0.4083],\n",
|
|
" [ 0.1076, 0.1579, 0.5573]], device='cuda:0')),\n",
|
|
" ('W_key.weight',\n",
|
|
" tensor([[-0.2604, 0.1829, -0.2569],\n",
|
|
" [ 0.4126, 0.4611, -0.5323]], device='cuda:0')),\n",
|
|
" ('W_value.weight',\n",
|
|
" tensor([[ 0.4929, 0.2757, 0.2516],\n",
|
|
" [ 0.2377, 0.4800, -0.0762]], device='cuda:0'))])"
|
|
]
|
|
},
|
|
"metadata": {},
|
|
"execution_count": 13
|
|
}
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"source": [
|
|
"- A `state_dict` is useful when saving and loading trained PyTorch models, for example\n",
|
|
"- In this particular case, saving and loading the `mask` is maybe not super useful, because it remains unchanged during training; so, for demonstration purposes, let's assume it was modified where all `1`'s were changed to `2`'s:"
|
|
],
|
|
"metadata": {
|
|
"id": "ACC-a1Hnt4Zv"
|
|
}
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"source": [
|
|
"ca_with_buffer.mask[ca_with_buffer.mask == 1.] = 2.\n",
|
|
"ca_with_buffer.mask"
|
|
],
|
|
"metadata": {
|
|
"colab": {
|
|
"base_uri": "https://localhost:8080/"
|
|
},
|
|
"id": "RLm1Sw0cuhvy",
|
|
"outputId": "4b2cc70f-1709-44e4-aa17-4e01353b86f8"
|
|
},
|
|
"execution_count": 14,
|
|
"outputs": [
|
|
{
|
|
"output_type": "execute_result",
|
|
"data": {
|
|
"text/plain": [
|
|
"tensor([[0., 2., 2., 2., 2., 2.],\n",
|
|
" [0., 0., 2., 2., 2., 2.],\n",
|
|
" [0., 0., 0., 2., 2., 2.],\n",
|
|
" [0., 0., 0., 0., 2., 2.],\n",
|
|
" [0., 0., 0., 0., 0., 2.],\n",
|
|
" [0., 0., 0., 0., 0., 0.]], device='cuda:0')"
|
|
]
|
|
},
|
|
"metadata": {},
|
|
"execution_count": 14
|
|
}
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"source": [
|
|
"- Then, if we save and load the model, we can see that the mask is restored with the modified value"
|
|
],
|
|
"metadata": {
|
|
"id": "BIkGgGqqvp4S"
|
|
}
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"source": [
|
|
"torch.save(ca_with_buffer.state_dict(), \"model.pth\")\n",
|
|
"\n",
|
|
"new_ca_with_buffer = CausalAttentionWithBuffer(d_in, d_out, context_length, 0.0)\n",
|
|
"new_ca_with_buffer.load_state_dict(torch.load(\"model.pth\"))\n",
|
|
"\n",
|
|
"new_ca_with_buffer.mask"
|
|
],
|
|
"metadata": {
|
|
"colab": {
|
|
"base_uri": "https://localhost:8080/"
|
|
},
|
|
"id": "e8g0QHUhuVBw",
|
|
"outputId": "cc7ee348-7f94-4117-e5cc-e0e01a94e906"
|
|
},
|
|
"execution_count": 15,
|
|
"outputs": [
|
|
{
|
|
"output_type": "execute_result",
|
|
"data": {
|
|
"text/plain": [
|
|
"tensor([[0., 2., 2., 2., 2., 2.],\n",
|
|
" [0., 0., 2., 2., 2., 2.],\n",
|
|
" [0., 0., 0., 2., 2., 2.],\n",
|
|
" [0., 0., 0., 0., 2., 2.],\n",
|
|
" [0., 0., 0., 0., 0., 2.],\n",
|
|
" [0., 0., 0., 0., 0., 0.]])"
|
|
]
|
|
},
|
|
"metadata": {},
|
|
"execution_count": 15
|
|
}
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"source": [
|
|
"- This is not true if we don't use buffers:"
|
|
],
|
|
"metadata": {
|
|
"id": "0pPaJk7bvBD7"
|
|
}
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"source": [
|
|
"ca_without_buffer.mask[ca_without_buffer.mask == 1.] = 2.\n",
|
|
"\n",
|
|
"torch.save(ca_without_buffer.state_dict(), \"model.pth\")\n",
|
|
"\n",
|
|
"new_ca_without_buffer = CausalAttentionWithoutBuffers(d_in, d_out, context_length, 0.0)\n",
|
|
"new_ca_without_buffer.load_state_dict(torch.load(\"model.pth\"))\n",
|
|
"\n",
|
|
"new_ca_without_buffer.mask"
|
|
],
|
|
"metadata": {
|
|
"colab": {
|
|
"base_uri": "https://localhost:8080/"
|
|
},
|
|
"id": "D03w8vDyvBRS",
|
|
"outputId": "28071601-120c-42da-b327-bb293793839f"
|
|
},
|
|
"execution_count": 16,
|
|
"outputs": [
|
|
{
|
|
"output_type": "execute_result",
|
|
"data": {
|
|
"text/plain": [
|
|
"tensor([[0., 1., 1., 1., 1., 1.],\n",
|
|
" [0., 0., 1., 1., 1., 1.],\n",
|
|
" [0., 0., 0., 1., 1., 1.],\n",
|
|
" [0., 0., 0., 0., 1., 1.],\n",
|
|
" [0., 0., 0., 0., 0., 1.],\n",
|
|
" [0., 0., 0., 0., 0., 0.]])"
|
|
]
|
|
},
|
|
"metadata": {},
|
|
"execution_count": 16
|
|
}
|
|
]
|
|
}
|
|
],
|
|
"metadata": {
|
|
"accelerator": "GPU",
|
|
"colab": {
|
|
"gpuType": "L4",
|
|
"provenance": []
|
|
},
|
|
"kernelspec": {
|
|
"display_name": "Python 3 (ipykernel)",
|
|
"language": "python",
|
|
"name": "python3"
|
|
},
|
|
"language_info": {
|
|
"codemirror_mode": {
|
|
"name": "ipython",
|
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"version": 3
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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|
"nbconvert_exporter": "python",
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|
"pygments_lexer": "ipython3",
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|
"version": "3.10.6"
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}
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},
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"nbformat": 4,
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"nbformat_minor": 0
|
|
} |