From 3ea18575c7af99356b52f884dc9dc6eec8c50852 Mon Sep 17 00:00:00 2001
From: yamashi <yamashi@users.noreply.github.com>
Date: Thu, 6 Apr 2023 13:49:12 +0200
Subject: [PATCH 1/8] Use flash attention monkeypatch

---
 finetune.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/finetune.py b/finetune.py
index f374e2b..998b1d6 100644
--- a/finetune.py
+++ b/finetune.py
@@ -16,6 +16,9 @@
         }
     ]
 """
+from monkeypatch.llama_flash_attn_monkey_patch import replace_llama_attn_with_flash_attn
+
+replace_llama_attn_with_flash_attn()
 
 import sys
 

From 7b18b39dd8f29545f3e728a7777a100cfe64bb0a Mon Sep 17 00:00:00 2001
From: yamashi <yamashi@users.noreply.github.com>
Date: Thu, 6 Apr 2023 13:49:36 +0200
Subject: [PATCH 2/8] Create llama_flash_attn_monkey_patch.py

---
 monkeypatch/llama_flash_attn_monkey_patch.py | 143 +++++++++++++++++++
 1 file changed, 143 insertions(+)
 create mode 100644 monkeypatch/llama_flash_attn_monkey_patch.py

diff --git a/monkeypatch/llama_flash_attn_monkey_patch.py b/monkeypatch/llama_flash_attn_monkey_patch.py
new file mode 100644
index 0000000..1d48bb5
--- /dev/null
+++ b/monkeypatch/llama_flash_attn_monkey_patch.py
@@ -0,0 +1,143 @@
+from typing import List, Optional, Tuple
+
+import torch
+from torch import nn
+
+import transformers
+from transformers.models.llama.modeling_llama import LlamaRotaryEmbedding, apply_rotary_pos_emb
+
+from einops import rearrange
+
+from flash_attn.flash_attn_interface import flash_attn_unpadded_qkvpacked_func
+from flash_attn.bert_padding import unpad_input, pad_input
+
+class LlamaAttention(nn.Module):
+    """Multi-headed attention from 'Attention Is All You Need' paper"""
+
+    def __init__(
+        self,
+        hidden_size: int,
+        num_heads: int,
+    ):
+        super().__init__()
+        self.hidden_size = hidden_size
+        self.num_heads = num_heads
+        self.head_dim = hidden_size // num_heads
+
+        if (self.head_dim * num_heads) != self.hidden_size:
+            raise ValueError(
+                f"hidden_size must be divisible by num_heads (got `hidden_size`: {self.hidden_size}"
+                f" and `num_heads`: {num_heads}).")
+        self.q_proj = nn.Linear(
+            hidden_size,
+            num_heads * self.head_dim,
+            bias=False,
+        )
+        self.k_proj = nn.Linear(
+            hidden_size,
+            num_heads * self.head_dim,
+            bias=False,
+        )
+        self.v_proj = nn.Linear(
+            hidden_size,
+            num_heads * self.head_dim,
+            bias=False,
+        )
+        self.o_proj = nn.Linear(
+            num_heads * self.head_dim,
+            hidden_size,
+            bias=False,
+        )
+        self.rotary_emb = LlamaRotaryEmbedding(self.head_dim)
+
+    def _shape(self, tensor: torch.Tensor, seq_len: int, bsz: int):
+        return tensor.view(bsz, seq_len, self.num_heads,
+                           self.head_dim).transpose(1, 2).contiguous()
+
+    def forward(
+        self,
+        hidden_states: torch.Tensor,
+        past_key_value: Optional[Tuple[torch.Tensor]] = None,
+        attention_mask: Optional[torch.Tensor] = None,
+        output_attentions: bool = False,
+        use_cache: bool = False,
+    ) -> Tuple[torch.Tensor, Optional[torch.Tensor],
+               Optional[Tuple[torch.Tensor]]]:
+        """Input shape: Batch x Time x Channel
+        
+        attention_mask: [bsz, q_len]
+        """
+        bsz, q_len, _ = hidden_states.size()
+
+        query_states = self.q_proj(hidden_states).view(
+            bsz, q_len, self.num_heads, self.head_dim).transpose(1, 2)
+        key_states = self.k_proj(hidden_states).view(
+            bsz, q_len, self.num_heads, self.head_dim).transpose(1, 2)
+        value_states = self.v_proj(hidden_states).view(
+            bsz, q_len, self.num_heads, self.head_dim).transpose(1, 2)
+        # [bsz, q_len, nh, hd]
+        # [bsz, nh, q_len, hd]
+
+        kv_seq_len = key_states.shape[-2]
+        offset = 0
+        if past_key_value is not None:
+            offset = past_key_value[0].shape[-2]
+            kv_seq_len += offset
+        cos, sin = self.rotary_emb(value_states, seq_len=kv_seq_len)
+        query_states, key_states = apply_rotary_pos_emb(query_states,
+                                                        key_states,
+                                                        cos,
+                                                        sin,
+                                                        offset=offset)
+        # [bsz, nh, t, hd]
+        assert not output_attentions, "output_attentions is not supported"
+        assert not use_cache, "use_cache is not supported"
+        assert past_key_value is None, "past_key_value is not supported"
+
+        # Flash attention codes from
+        # https://github.com/HazyResearch/flash-attention/blob/main/flash_attn/flash_attention.py
+
+        # transform the data into the format required by flash attention
+        qkv = torch.stack([query_states, key_states, value_states], dim=2) # [bsz, nh, 3, q_len, hd]
+        qkv = qkv.transpose(1, 3) # [bsz, q_len, 3, nh, hd]
+        # We have disabled _prepare_decoder_attention_mask in LlamaModel
+        # the attention_mask should be the same as the key_padding_mask
+        key_padding_mask = attention_mask
+
+
+        if key_padding_mask is None:
+            qkv = rearrange(qkv, 'b s ... -> (b s) ...')
+            max_s = q_len
+            cu_q_lens = torch.arange(0, (bsz + 1) * q_len, step=q_len, dtype=torch.int32,
+                                    device=qkv.device)
+            output = flash_attn_unpadded_qkvpacked_func(
+                qkv, cu_q_lens, max_s, 0.0,
+                softmax_scale=None, causal=True
+            )
+            output = rearrange(output, '(b s) ... -> b s ...', b=bsz)
+        else:
+            nheads = qkv.shape[-2]
+            x = rearrange(qkv, 'b s three h d -> b s (three h d)')
+            x_unpad, indices, cu_q_lens, max_s = unpad_input(x, key_padding_mask)
+            x_unpad = rearrange(x_unpad, 'nnz (three h d) -> nnz three h d', three=3, h=nheads)
+            output_unpad = flash_attn_unpadded_qkvpacked_func(
+                x_unpad, cu_q_lens, max_s, 0.0,
+                softmax_scale=None, causal=True
+            )
+            output = rearrange(pad_input(rearrange(output_unpad, 'nnz h d -> nnz (h d)'),
+                                        indices, bsz, q_len),
+                            'b s (h d) -> b s h d', h=nheads)
+        return self.o_proj(rearrange(output,
+                                     'b s h d -> b s (h d)')), None, None
+
+
+# Copied from transformers.models.bart.modeling_bart.BartDecoder._prepare_decoder_attention_mask
+def _prepare_decoder_attention_mask(self, attention_mask, input_shape,
+                                    inputs_embeds, past_key_values_length):
+    # [bsz, seq_len]
+    return attention_mask
+
+
+def replace_llama_attn_with_flash_attn():
+    transformers.models.llama.modeling_llama.LlamaModel._prepare_decoder_attention_mask = _prepare_decoder_attention_mask
+    transformers.models.llama.modeling_llama.LlamaAttention = LlamaAttention

From 30bf938d03ada62a680820529b0db025484a67c1 Mon Sep 17 00:00:00 2001
From: yamashi <yamashi@users.noreply.github.com>
Date: Thu, 6 Apr 2023 13:50:25 +0200
Subject: [PATCH 3/8] Update requirements.txt

---
 requirements.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/requirements.txt b/requirements.txt
index 605c0d1..2db1f01 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,6 +4,7 @@ bitsandbytes
 datasets
 sentencepiece
 safetensors
+flash-attn
 git+https://github.com/huggingface/transformers.git
 git+https://github.com/sterlind/GPTQ-for-LLaMa.git@lora_4bit
 git+https://github.com/sterlind/peft.git

From 7770e76c9c143eaab04657d082d3f3406ebede71 Mon Sep 17 00:00:00 2001
From: yamashi <yamashi@users.noreply.github.com>
Date: Thu, 6 Apr 2023 17:32:01 +0200
Subject: [PATCH 4/8] Fix args of flash attention

---
 monkeypatch/llama_flash_attn_monkey_patch.py | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/monkeypatch/llama_flash_attn_monkey_patch.py b/monkeypatch/llama_flash_attn_monkey_patch.py
index 1d48bb5..dd2589d 100644
--- a/monkeypatch/llama_flash_attn_monkey_patch.py
+++ b/monkeypatch/llama_flash_attn_monkey_patch.py
@@ -4,7 +4,7 @@ import torch
 from torch import nn
 
 import transformers
-from transformers.models.llama.modeling_llama import LlamaRotaryEmbedding, apply_rotary_pos_emb
+from transformers.models.llama.modeling_llama import LlamaConfig, LlamaRotaryEmbedding, apply_rotary_pos_emb
 
 from einops import rearrange
 
@@ -16,13 +16,14 @@ class LlamaAttention(nn.Module):
 
     def __init__(
         self,
-        hidden_size: int,
-        num_heads: int,
+        config: LlamaConfig,
     ):
         super().__init__()
+        hidden_size = config.hidden_size
+        num_heads = config.num_attention_heads
         self.hidden_size = hidden_size
         self.num_heads = num_heads
-        self.head_dim = hidden_size // num_heads
+        self.head_dim = self.hidden_size // num_heads
 
         if (self.head_dim * num_heads) != self.hidden_size:
             raise ValueError(

From 2bf5d42f287127427e09951c78c4b023203b7b22 Mon Sep 17 00:00:00 2001
From: yamashi <yamashi@users.noreply.github.com>
Date: Thu, 6 Apr 2023 17:46:15 +0200
Subject: [PATCH 5/8] Add position_ids to flash attention

---
 monkeypatch/llama_flash_attn_monkey_patch.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/monkeypatch/llama_flash_attn_monkey_patch.py b/monkeypatch/llama_flash_attn_monkey_patch.py
index dd2589d..0c80227 100644
--- a/monkeypatch/llama_flash_attn_monkey_patch.py
+++ b/monkeypatch/llama_flash_attn_monkey_patch.py
@@ -60,6 +60,7 @@ class LlamaAttention(nn.Module):
         hidden_states: torch.Tensor,
         past_key_value: Optional[Tuple[torch.Tensor]] = None,
         attention_mask: Optional[torch.Tensor] = None,
+        position_ids: Optional[torch.LongTensor] = None,
         output_attentions: bool = False,
         use_cache: bool = False,
     ) -> Tuple[torch.Tensor, Optional[torch.Tensor],
@@ -80,16 +81,15 @@ class LlamaAttention(nn.Module):
         # [bsz, nh, q_len, hd]
 
         kv_seq_len = key_states.shape[-2]
-        offset = 0
         if past_key_value is not None:
-            offset = past_key_value[0].shape[-2]
-            kv_seq_len += offset
+            kv_seq_len += past_key_value[0].shape[-2]
+
         cos, sin = self.rotary_emb(value_states, seq_len=kv_seq_len)
         query_states, key_states = apply_rotary_pos_emb(query_states,
                                                         key_states,
                                                         cos,
                                                         sin,
-                                                        offset=offset)
+                                                        position_ids)
         # [bsz, nh, t, hd]
         assert not output_attentions, "output_attentions is not supported"
         assert not use_cache, "use_cache is not supported"

From 778035152d7ba63a2f980eea98142d5e6eec7fe3 Mon Sep 17 00:00:00 2001
From: yamashi <yamashi@users.noreply.github.com>
Date: Fri, 7 Apr 2023 00:42:34 +0200
Subject: [PATCH 6/8] Update arg_parser.py

---
 arg_parser.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arg_parser.py b/arg_parser.py
index a985380..be18154 100644
--- a/arg_parser.py
+++ b/arg_parser.py
@@ -66,6 +66,8 @@ def parse_commandline():
 
     # Multi GPU Support
     parser_training.add_argument("--local_rank", type=int, default=0, help="local rank if using torch.distributed.launch")
+    
+    parser_training.add_argument("--flash_attention", help="enables flash attention, can improve performance and reduce VRAM use")
 
     return vars(parser.parse_args())
 
@@ -102,4 +104,5 @@ def get_config() -> Finetune4bConfig:
         use_eos_token=args["use_eos_token"]!=0,
         groupsize=args["groupsize"],
         local_rank=args["local_rank"],
+        flash_attention=args["flash_attention"],
     )

From 95cd390d2528dcaaa618b6c2f4765b136e4e313b Mon Sep 17 00:00:00 2001
From: yamashi <yamashi@users.noreply.github.com>
Date: Fri, 7 Apr 2023 00:43:15 +0200
Subject: [PATCH 7/8] Update Finetune4bConfig.py

---
 Finetune4bConfig.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Finetune4bConfig.py b/Finetune4bConfig.py
index a8a33bf..09c535c 100644
--- a/Finetune4bConfig.py
+++ b/Finetune4bConfig.py
@@ -15,7 +15,7 @@ class Finetune4bConfig:
                  warmup_steps: int, save_steps: int, save_total_limit: int, logging_steps: int,
                  checkpoint: bool, skip: bool, verbose: bool,
                  txt_row_thd: int, use_eos_token: bool, groupsize: int,
-                 local_rank: int,
+                 local_rank: int, flash_attention: bool
                  ):
         """
         Args:
@@ -48,6 +48,7 @@ class Finetune4bConfig:
             use_eos_token (bool): Use Eos token instead of padding with 0
             groupsize (int): Group size of V2 model, use -1 to load V1 model
             local_rank (int): local rank if using torch.distributed.launch
+            flash_attention (bool): Enables flash attention
         """
         self.dataset = dataset
         self.ds_type = ds_type
@@ -84,6 +85,7 @@ class Finetune4bConfig:
         if self.ddp:
             self.gradient_accumulation_steps = self.gradient_accumulation_steps // self.world_size
         self.groupsize = groupsize
+        self.flash_attention = flash_attention
 
 
     def __str__(self) -> str:

From c5aa7fb6951ac573089daf7a1aa990bc68270f1f Mon Sep 17 00:00:00 2001
From: yamashi <yamashi@users.noreply.github.com>
Date: Fri, 7 Apr 2023 00:43:36 +0200
Subject: [PATCH 8/8] Update finetune.py

---
 finetune.py | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/finetune.py b/finetune.py
index 998b1d6..eea0e66 100644
--- a/finetune.py
+++ b/finetune.py
@@ -16,9 +16,13 @@
         }
     ]
 """
-from monkeypatch.llama_flash_attn_monkey_patch import replace_llama_attn_with_flash_attn
+# Early load config to replace attn if needed
+from arg_parser import get_config
+ft_config = get_config()
 
-replace_llama_attn_with_flash_attn()
+if ft_config.flash_attention:
+    from monkeypatch.llama_flash_attn_monkey_patch import replace_llama_attn_with_flash_attn
+    replace_llama_attn_with_flash_attn()
 
 import sys
 
@@ -32,10 +36,9 @@ from autograd_4bit import load_llama_model_4bit_low_ram
 from peft import LoraConfig, get_peft_model, get_peft_model_state_dict, PeftModel
 
 # ! Config
-from arg_parser import get_config
 import train_data
 
-ft_config = get_config()
+
 
 # * Show loaded parameters
 if ft_config.local_rank == 0: