Enable Flash Attention in recompute and causal modes (#21)

* Enable Flash Attention in recompute and causal modes

* Add flash_attention_causal_mask to generation utils

* Propagate Flash Attention causal_mask to finetuning example

* Modify README example and provide additional description

* Add flash_attention_causal_mask to FT README

Author: wszczurekhabana

examples/language-modeling/README.md

@@ -552,7 +552,8 @@ python3 ../gaudi_spawn.py --use_deepspeed  --world_size 8  run_lora_clm.py \
   --lora_rank 4 \
   --lora_target_modules "q_proj" "v_proj" "k_proj" "o_proj" \
   --validation_split_percentage 4 \
-  --use_flash_attention True
+  --use_flash_attention True \
+  --flash_attention_causal_mask True
 ```
 
 - Multi-card finetuning of Falcon-180B:

examples/language-modeling/run_lora_clm.py

@@ -156,6 +156,15 @@ class ModelArguments:
             )
         },
     )
+    flash_attention_causal_mask: bool = field(
+        default=False,
+        metadata={
+            "help": (
+                "Whether to enable causal mask in Habana flash attention for fine-tuning."
+                " It is applicable only when use_flash_attention is True.",
+            )
+        },
+    )
     use_fused_rope: bool = field(
         default=True,
         metadata={
@@ -545,6 +554,7 @@ def main():
         if model_args.use_flash_attention:
             model.generation_config.use_flash_attention = True
             model.generation_config.flash_attention_recompute = model_args.flash_attention_recompute
+            model.generation_config.flash_attention_causal_mask = model_args.flash_attention_causal_mask
         if not model_args.use_fused_rope:
             model.generation_config.use_fused_rope = False
 

examples/text-generation/README.md

@@ -296,6 +296,30 @@ QUANT_CONFIG=./quantization_config/maxabs_quant.json python ../gaudi_spawn.py \
 ```
 `--fp8` is required to enable quantization in fp8.
 
+### Using Habana Flash Attention
+
+Habana Flash Attention addresses large sequence lenghts on prompt stage of inference. Using causal attention mask on prompt stage requires input sequences in batch to be of the same length, but can provide a memory saving, thus enabling higher batch sizes.
+
+Below example uses `flash_attention_recompute` mode in order to reduce memory consumption on prompt stage. Additionally since all sequences in a batch are of the same lenght it uses `flash_attention_causal_mask` which will further improve performance by taking advantage of specific lower-diagonal shape of inputs to softmax operation.
+
+```bash
+python ../gaudi_spawn.py --use_deepspeed --world_size 8 run_generation.py \
+--model_name_or_path meta-llama/Llama-2-70b-hf \
+--use_hpu_graphs \
+--use_kv_cache \
+--reuse_cache \
+--trim_logits \
+--attn_softmax_bf16 \
+--max_input_tokens 31744 \
+--max_new_tokens 1024 \
+--batch_size=12 \
+--use_flash_attention \
+--flash_attention_recompute \
+--flash_attention_causal_mask \
+--book_source
+```
+
+For more details see [documentation](https://docs.habana.ai/en/latest/PyTorch/Model_Optimization_PyTorch/Optimization_in_PyTorch_Models.html#using-fused-sdpa).
 
 ## Language Model Evaluation Harness
 

examples/text-generation/run_generation.py

@@ -232,6 +232,21 @@ def setup_parser(parser):
         action="store_true",
         help="Whether to enable Habana Flash Attention, provided that the model supports it.",
     )
+    parser.add_argument(
+        "--flash_attention_recompute",
+        action="store_true",
+        help="Whether to enable Habana Flash Attention in recompute mode on first token generation. This gives an opportunity of splitting graph internally which helps reduce memory consumption.",
+    )
+    parser.add_argument(
+        "--flash_attention_causal_mask",
+        action="store_true",
+        help="Whether to enable Habana Flash Attention in causal mode on first token generation.",
+    )
+    parser.add_argument(
+        "--book_source",
+        action="store_true",
+        help="Whether to use project Guttenberg books data as input. Usefull for testing large sequence lenghts.",
+    )
     parser.add_argument(
         "--torch_compile",
         action="store_true",
@@ -271,6 +286,45 @@ def main():
         # Benchmark over the prompts below
         if args.prompt:
             input_sentences = args.prompt
+        elif args.book_source:
+
+            def download_book(book_id):
+                import os
+
+                import requests
+
+                url = f"https://www.gutenberg.org/cache/epub/{book_id}/pg{book_id}.txt"
+                response = requests.get(url)
+                if response.status_code == 200:
+                    pid = os.getpid()
+                    save_path = f"/tmp/{book_id}_{pid}.txt"
+                    with open(save_path, "wb") as file:
+                        file.write(response.content)
+                    print(f"Book downloaded and saved to: {save_path}")
+                    return save_path
+                else:
+                    print("Failed to download book! Exiting...")
+                    import sys
+
+                    sys.exit()
+
+            def assemble_prompt(prompt_size, book_path):
+                prompt = ""
+                counter = 0
+                book_lines = open(book_path).readlines()
+                for line in book_lines:
+                    for word in line.split():
+                        counter += 1
+                        prompt += word + " "
+                        if counter == prompt_size:
+                            return [prompt] * args.batch_size
+
+            book_ids = [
+                2701,  # Moby Dick; Or, The Whale
+                1513,  # Romeo and Juliet
+                1342,  # Pride and Prejudice
+            ]
+            input_sentences = assemble_prompt(prompt_size=args.max_input_tokens, book_path=download_book(book_ids[0]))
         else:
             input_sentences = [
                 "DeepSpeed is a machine learning framework",

examples/text-generation/utils.py

@@ -347,6 +347,8 @@ def setup_generation_config(args, model, tokenizer):
         assert generation_config.bucket_size > 0
     generation_config.kv_cache_fp8 = args.kv_cache_fp8
     generation_config.use_flash_attention = args.use_flash_attention
+    generation_config.flash_attention_recompute = args.flash_attention_recompute
+    generation_config.flash_attention_causal_mask = args.flash_attention_causal_mask
     return generation_config
 
 

optimum/habana/transformers/generation/configuration_utils.py

@@ -33,6 +33,8 @@ class GaudiGenerationConfig(GenerationConfig):
         Whether to use flash attention optimization.
     flash_attention_recompute (`bool`, *optional*):
         Whether to enable recompute if use Habana flash attention.
+    flash_attention_causal_mask (`bool`, *optional*):
+        Whether to enable causal_mask if use Habana flash attention.
     """
 
     def __init__(self, **kwargs):
@@ -49,4 +51,5 @@ def __init__(self, **kwargs):
         self.kv_cache_fp8 = kwargs.get("kv_cache_fp8", None)
         self.use_flash_attention = kwargs.get("use_flash_attention", None)
         self.flash_attention_recompute = kwargs.get("flash_attention_recompute", None)
+        self.flash_attention_causal_mask = kwargs.get("flash_attention_causal_mask", None)
         self.use_fused_rope = kwargs.get("use_fused_rope", None)

optimum/habana/transformers/generation/utils.py

@@ -707,6 +707,7 @@ def generate(
         # determine whether flash attention needs to be used
         model_kwargs["use_flash_attention"] = generation_config.use_flash_attention
         model_kwargs["flash_attention_recompute"] = True if generation_config.flash_attention_recompute else False
+        model_kwargs["flash_attention_causal_mask"] = True if generation_config.flash_attention_causal_mask else False
         model_kwargs["use_fused_rope"] = False if not generation_config.use_fused_rope else True
 
         if not self.config.is_encoder_decoder:

optimum/habana/transformers/models/llama/modeling_llama.py

@@ -207,6 +207,7 @@ def pre_attn_forward(
         reuse_cache: Optional[bool] = False,
         use_flash_attention: Optional[bool] = False,
         flash_attention_recompute: Optional[bool] = False,
+        flash_attention_causal_mask: Optional[bool] = False,
         cache_idx: int = None,
         use_fused_rope: Optional[bool] = True,
         **kwargs,
@@ -220,6 +221,7 @@ def pre_attn_forward(
         - add new args reuse_cache
         - add new args use_flash_attention
         - add new arg flash_attention_recompute
+        - add new arg flash_attention_causal_mask
         """
         if "padding_mask" in kwargs:
             warnings.warn(
@@ -310,10 +312,15 @@ def pre_attn_forward(
                     )
             else:
                 # first token
-                with ht.sdp_kernel(enable_recompute=flash_attention_recompute):
-                    attn_output = FusedSDPA.apply(
-                        query_states, key_states, value_states, attention_mask, 0.0, False, None
-                    )
+                if flash_attention_causal_mask:
+                    # causal masking on first token requires inputs to be of the same lenght
+                    with ht.sdp_kernel(enable_recompute=flash_attention_recompute):
+                        attn_output = FusedSDPA.apply(query_states, key_states, value_states, None, 0.0, True, None)
+                else:
+                    with ht.sdp_kernel(enable_recompute=flash_attention_recompute):
+                        attn_output = FusedSDPA.apply(
+                            query_states, key_states, value_states, attention_mask, 0.0, False, None
+                        )
 
         else:
             query_states, key_states, value_states, attention_mask = gaudi_llama_repeat_kv(
@@ -455,6 +462,7 @@ def forward(
         reuse_cache: Optional[bool] = False,
         use_flash_attention: Optional[bool] = False,
         flash_attention_recompute: Optional[bool] = False,
+        flash_attention_causal_mask: Optional[bool] = False,
         cache_idx: int = None,
         use_fused_rope: Optional[bool] = True,
         **kwargs,
@@ -467,6 +475,7 @@ def forward(
         - add new args reuse_cache
         - add new args use_flash_attention
         - add new arg flash_attention_recompute
+        - add new arg flash_attention_causal_mask
         """
         if "padding_mask" in kwargs:
             warnings.warn(
@@ -486,6 +495,7 @@ def forward(
             reuse_cache,
             use_flash_attention=use_flash_attention,
             flash_attention_recompute=flash_attention_recompute,
+            flash_attention_causal_mask=flash_attention_causal_mask,
             cache_idx=cache_idx,
             use_fused_rope=use_fused_rope,
             **kwargs,
@@ -517,6 +527,7 @@ def pre_attn(
         reuse_cache: Optional[bool] = False,
         use_flash_attention: Optional[bool] = False,
         flash_attention_recompute: Optional[bool] = False,
+        flash_attention_causal_mask: Optional[bool] = False,
         cache_idx: int = None,
         use_fused_rope: Optional[bool] = True,
     ) -> Tuple[torch.FloatTensor, Optional[Tuple[torch.FloatTensor, torch.FloatTensor]]]:
@@ -533,6 +544,7 @@ def pre_attn(
             reuse_cache,
             use_flash_attention,
             flash_attention_recompute,
+            flash_attention_causal_mask,
             cache_idx=cache_idx,
             use_fused_rope=use_fused_rope,
         )
@@ -583,6 +595,7 @@ def forward(
         reuse_cache: Optional[bool] = False,
         use_flash_attention: Optional[bool] = False,
         flash_attention_recompute: Optional[bool] = False,
+        flash_attention_causal_mask: Optional[bool] = False,
         cache_idx: int = None,
         use_fused_rope: Optional[bool] = True,
     ) -> Union[Tuple, BaseModelOutputWithPast]:
@@ -594,6 +607,7 @@ def forward(
         - add new args reuse_cache
         - add new args use_flash_attention
         - add new arg flash_attention_recompute
+        - add new arg flash_attention_causal_mask
         """
         output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
         output_hidden_states = (
@@ -702,6 +716,7 @@ def forward(
                     reuse_cache=reuse_cache,
                     use_flash_attention=use_flash_attention,
                     flash_attention_recompute=flash_attention_recompute,
+                    flash_attention_causal_mask=flash_attention_causal_mask,
                     cache_idx=cache_idx,
                     use_fused_rope=use_fused_rope,
                 )
@@ -777,6 +792,7 @@ def forward(
         reuse_cache: Optional[bool] = False,
         use_flash_attention: Optional[bool] = False,
         flash_attention_recompute: Optional[bool] = False,
+        flash_attention_causal_mask: Optional[bool] = False,
         cache_idx: int = None,
         use_fused_rope: Optional[bool] = True,
     ) -> Union[Tuple, CausalLMOutputWithPast]:
@@ -801,6 +817,7 @@ def forward(
             reuse_cache=reuse_cache,
             use_flash_attention=use_flash_attention,
             flash_attention_recompute=flash_attention_recompute,
+            flash_attention_causal_mask=flash_attention_causal_mask,
             cache_idx=cache_idx,
             use_fused_rope=use_fused_rope,
         )
@@ -914,6 +931,7 @@ def prepare_inputs_for_generation(
                 "reuse_cache": reuse_cache,
                 "use_flash_attention": kwargs.get("use_flash_attention"),
                 "flash_attention_recompute": kwargs.get("flash_attention_recompute"),
+                "flash_attention_causal_mask": kwargs.get("flash_attention_causal_mask"),
                 "cache_idx": kwargs.get("cache_idx"),
             }
         )

optimum/habana/transformers/trainer.py

@@ -909,6 +909,8 @@ def hpu_deepspeed_checkpointing(function, *checkpoint_args):
                             inputs["use_flash_attention"] = True
                         if self.model.generation_config.flash_attention_recompute:
                             inputs["flash_attention_recompute"] = True
+                        if self.model.generation_config.flash_attention_causal_mask:
+                            inputs["flash_attention_causal_mask"] = True
                         if not self.model.generation_config.use_fused_rope:
                             inputs["use_fused_rope"] = False
 
@@ -1686,6 +1688,8 @@ def evaluation_loop(
                         inputs["use_flash_attention"] = True
                     if self.model.generation_config.flash_attention_recompute:
                         inputs["flash_attention_recompute"] = True
+                    if self.model.generation_config.flash_attention_causal_mask:
+                        inputs["flash_attention_causal_mask"] = True
                     if not self.model.generation_config.use_fused_rope:
                         inputs["use_fused_rope"] = False