Adding support for BlockedKV attention in CasualLM models

QEfficient/customop/__init__.py

@@ -5,8 +5,15 @@
 #
 # -----------------------------------------------------------------------------
 
-from QEfficient.customop.ctx_scatter_gather import CtxGatherFunc, CtxGatherFunc3D, CtxScatterFunc, CtxScatterFunc3D
+from QEfficient.customop.ctx_scatter_gather import (
+    CtxGatherFunc,
+    CtxGatherFunc3D,
+    CtxGatherFuncBlockedKV,
+    CtxScatterFunc,
+    CtxScatterFunc3D,
+)
 from QEfficient.customop.ctx_scatter_gather_cb import (
+    CtxGatherFuncBlockedKVCB,
     CtxGatherFuncCB,
     CtxGatherFuncCB3D,
     CtxScatterFuncCB,
@@ -16,12 +23,14 @@
 
 __all__ = [
     "CtxGatherFunc",
+    "CtxGatherFuncBlockedKV",
     "CtxScatterFunc",
     "CtxGatherFunc3D",
     "CtxScatterFunc3D",
     "CustomRMSNormAIC",
     "GemmaCustomRMSNormAIC",
     "CtxGatherFuncCB",
+    "CtxGatherFuncBlockedKVCB",
     "CtxScatterFuncCB",
     "CtxGatherFuncCB3D",
     "CtxScatterFuncCB3D",

QEfficient/customop/ctx_scatter_gather.py

@@ -145,3 +145,29 @@ def setup_context(ctx, inputs, outputs):
     @staticmethod
     def symbolic(g: torch.Graph, data: torch.Value, ctx_indices: torch.Value, comp_ctx_len: int) -> torch.Value:
         return g.onnxscript_op(CtxGather, data, ctx_indices, comp_ctx_len).setTypeAs(data)
+
+
+@onnxscript.script(onnxscript.values.Opset("com.qualcomm.cloud", 1))
+def CtxGatherBlockedKV(data: onnxscript.FLOAT, ctx_indices: onnxscript.INT32) -> onnxscript.FLOAT:
+    ctx_indices = ops.Unsqueeze(ctx_indices, [-1])
+    return ops.GatherND(data, ctx_indices, batch_dims=2)
+
+
+class CtxGatherFuncBlockedKV(torch.autograd.Function):
+    """
+    Function to gather only the valid key values from KV-cache.
+    """
+
+    @staticmethod
+    def forward(data: torch.Tensor, ctx_indices: torch.Tensor):
+        batch_indices = torch.arange(data.shape[0]).view(-1, 1, 1)
+        head_indices = torch.arange(data.shape[1]).view(1, -1, 1)
+        return data[batch_indices, head_indices, ctx_indices]
+
+    @staticmethod
+    def setup_context(ctx, inputs, outputs):
+        pass
+
+    @staticmethod
+    def symbolic(g: torch.Graph, data: torch.Value, ctx_indices: torch.Value) -> torch.Value:
+        return g.onnxscript_op(CtxGatherBlockedKV, data, ctx_indices).setTypeAs(data)

QEfficient/customop/ctx_scatter_gather_cb.py

@@ -139,6 +139,44 @@ def symbolic(
         return g.onnxscript_op(CtxGatherCB, data, batch_index, ctx_indices, comp_ctx_len).setTypeAs(data)
 
 
+@onnxscript.script(onnxscript.values.Opset("com.qualcomm.cloud", 1))
+def CtxGatherBlockedKVCB(
+    data: onnxscript.FLOAT, batch_index: onnxscript.INT32, ctx_indices: onnxscript.INT32
+) -> onnxscript.FLOAT:
+    batch_size = ops.Gather(ops.Shape(batch_index), [0])
+    num_heads = ops.Gather(ops.Shape(data), [1])
+    ctx_len = ops.Gather(ops.Shape(ctx_indices), [2])
+
+    # Expanded shape to create indices
+    zero = ops.Constant(value_ints=[0])
+    one = ops.Constant(value_ints=[1])
+    exp_shape = ops.Concat(batch_size, num_heads, ctx_len, one, axis=0)
+
+    # Create indices
+    batch_idx = ops.Expand(ops.Unsqueeze(batch_index, [2, 3]), exp_shape)
+    head_idx = ops.Expand(ops.Unsqueeze(ops.Range(zero, num_heads, one), [0, 2, 3]), exp_shape)
+    ctx_idx = ops.Expand(ops.Unsqueeze(ctx_indices, [3]), exp_shape)
+    indices = ops.Concat(batch_idx, head_idx, ctx_idx, axis=3)
+
+    return ops.GatherND(data, indices)
+
+
+class CtxGatherFuncBlockedKVCB(torch.autograd.Function):
+    @staticmethod
+    def forward(data: torch.Tensor, batch_index: torch.Tensor, ctx_indices: torch.Tensor):
+        batch_indices = batch_index.view(-1, 1, 1)
+        head_indices = torch.arange(data.shape[1]).view(1, -1, 1)
+        return data[batch_indices, head_indices, ctx_indices]
+
+    @staticmethod
+    def setup_context(ctx, inputs, outputs):
+        pass
+
+    @staticmethod
+    def symbolic(g: torch.Graph, data: torch.Value, batch_index: torch.Value, ctx_indices: torch.Value) -> torch.Value:
+        return g.onnxscript_op(CtxGatherBlockedKVCB, data, batch_index, ctx_indices).setTypeAs(data)
+
+
 @onnxscript.script(onnxscript.values.Opset("com.qualcomm.cloud", 1))
 def CtxGatherCB3D(
     data: onnxscript.FLOAT, batch_index: onnxscript.INT32, ctx_indices: onnxscript.INT32

QEfficient/transformers/cache_utils.py

@@ -15,6 +15,8 @@
 from QEfficient.customop import (
     CtxGatherFunc,
     CtxGatherFunc3D,
+    CtxGatherFuncBlockedKV,
+    CtxGatherFuncBlockedKVCB,
     CtxGatherFuncCB,
     CtxGatherFuncCB3D,
     CtxScatterFunc,
@@ -85,6 +87,49 @@ def read_only(self, cache_kwargs):
             v_out = CtxGatherFunc.apply(v_out, ctx_indices, ctx_len)
 
         v_out = torch.where(invalid_mask.unsqueeze(-1), torch.tensor(0.0, dtype=torch.float32), v_out)
+
+    def read_only_blockedKV(self, start_index, end_index, cache_kwargs):
+        """
+        Reads the `key_states` and `value_states` for the layer for each KV block.
+
+        Parameters:
+            cache_kwargs (`Dict[str, Any]`, `optional`):
+                Additional arguments for the cache subclass. No additional arguments are used in `DynamicCache`.
+
+            start_index (`int`):
+                Start index of the K/V block to read
+
+            end_index (`int`):
+                End index of the K/V block to read
+
+        Return:
+            A tuple containing the updated key and value states.
+        """
+        # Gather
+        k_out, v_out = self.keys, self.values
+        position_ids = cache_kwargs.get("position_ids")
+        batch_index = cache_kwargs.get("batch_index", None)
+        batch, num_kv_heads, _, _ = k_out.shape
+        ctx_indices = torch.arange(start=start_index, end=end_index)[None, None, ...]
+        gather_limit = position_ids.max(1, keepdim=True).values.unsqueeze(1)
+        invalid_mask = ctx_indices > gather_limit
+
+        if torch.onnx.is_in_onnx_export():
+            invalid_idx_value = torch.iinfo(torch.int32).max
+        else:
+            invalid_idx_value = 0
+
+        ctx_indices = torch.where(invalid_mask, invalid_idx_value, ctx_indices)
+
+        if batch_index is not None:
+            k_out = CtxGatherFuncBlockedKVCB.apply(k_out, batch_index, ctx_indices)
+            v_out = CtxGatherFuncBlockedKVCB.apply(v_out, batch_index, ctx_indices)
+        else:
+            ctx_indices = ctx_indices.expand(batch, num_kv_heads, ctx_indices.shape[-1])
+            k_out = CtxGatherFuncBlockedKV.apply(k_out, ctx_indices)
+            v_out = CtxGatherFuncBlockedKV.apply(v_out, ctx_indices)
+
+        v_out = torch.where(invalid_mask.unsqueeze(-1), torch.tensor(0.0, dtype=torch.float32), v_out)
         return k_out, v_out
 
     def write_only(self, key_states, value_states, cache_kwargs):
@@ -284,6 +329,25 @@ def read_only(self, layer_idx, cache_kwargs):
         """
         return self.layers[layer_idx].read_only(cache_kwargs)
 
+    def read_only_blockedKV(self, start_index, end_index, layer_idx, cache_kwargs):
+        """
+        Reads the `key_states` and `value_states` for the layer `layer_idx`.
+
+        Parameters:
+            start_index (`int`):
+                Start index of the K/V block to read
+            end_index (`int`):
+                End index of the K/V block to read
+            layer_idx (`int`):
+                The index of the layer to cache the states for.
+            cache_kwargs (`Dict[str, Any]`, `optional`):
+                Additional arguments for the cache subclass. No additional arguments are used in `DynamicCache`.
+
+        Return:
+            A tuple containing the updated key and value states.
+        """
+        return self.layers[layer_idx].read_only_blockedKV(start_index, end_index, cache_kwargs)
+
     def write_only(self, key_states, value_states, layer_idx, cache_kwargs):
         """
         Write in the cache with the new `key_states` and `value_states` for the layer `layer_idx`.

QEfficient/transformers/modeling_attn_mask_utils.py

@@ -14,6 +14,7 @@ def _create_causal_mask(
     position_ids,
     target_length,
     sliding_window: Optional[int] = None,
+    start_index: Optional[int] = 0,
 ):
     """
     A utility attention mask class that allows one to:
@@ -40,7 +41,7 @@ def _create_causal_mask(
         attention_mask = attention_mask.unsqueeze(1)
     else:
         query_indices = position_ids.unsqueeze(-1)
-        kv_indices = torch.arange(target_length).view(1, 1, -1)
+        kv_indices = torch.arange(start=start_index, end=target_length).view(1, 1, -1)
         attention_mask = kv_indices > query_indices
         attention_mask = attention_mask.unsqueeze(1)
 

QEfficient/transformers/models/llama/modeling_llama.py

@@ -5,7 +5,7 @@
 #
 # -----------------------------------------------------------------------------
 
-from typing import List, Optional, Tuple, Union
+from typing import Any, Dict, List, Optional, Tuple, Union
 
 import torch
 from torch import nn
@@ -113,13 +113,88 @@ def eager_attention_forward(
         attn_weights = torch.where(
             attention_mask, torch.tensor(MIN_MASKED_ATTENTION_VALUE, dtype=torch.float32), attn_weights
         )
+
     attn_weights = nn.functional.softmax(attn_weights, dim=-1, dtype=torch.float32).to(query.dtype)
     attn_output = torch.matmul(attn_weights, value_states)
     attn_output = attn_output.transpose(1, 2).contiguous()
 
     return attn_output, attn_weights
 
 
+def eager_attention_forward_blockedKV(
+    module: nn.Module,
+    query: torch.Tensor,
+    key: torch.Tensor,
+    value: torch.Tensor,
+    attention_mask: Optional[torch.Tensor],
+    scaling: float,
+    num_kv_blocks: Optional[torch.Tensor] = None,
+    cache_kwargs: Optional[Dict[str, Any]] = None,
+    layer_idx: int = None,
+    past_key_value: Optional[Cache] = None,
+    **kwargs,
+):
+    # Initialize result tensor
+    output = torch.zeros_like(query)
+
+    # Initialize Running Maximum
+    batch_size, num_heads, seq_len, _ = query.shape
+    current_max = torch.full((batch_size, num_heads, seq_len), float(MIN_MASKED_ATTENTION_VALUE))
+
+    # Initialize Denominator
+    current_denominator = torch.zeros(batch_size, num_heads, seq_len)
+
+    past_seen_tokens = cache_kwargs.get("past_seen_tokens")
+    position_ids = cache_kwargs.get("position_ids")
+    block_size = -(-past_seen_tokens // num_kv_blocks)
+    masked_tensor = torch.tensor(MIN_MASKED_ATTENTION_VALUE, dtype=torch.float32)
+
+    for j in range(num_kv_blocks):
+        start_index = j * block_size
+        end_index = (j + 1) * block_size
+        K_block, V_block = past_key_value.read_only_blockedKV(start_index, end_index, layer_idx, cache_kwargs)
+        K_block_states = repeat_kv(K_block, module.num_key_value_groups)
+        V_block_states = repeat_kv(V_block, module.num_key_value_groups)
+        past_seen_tokens_start = start_index
+        past_seen_tokens_end = torch.where(
+            torch.tensor(past_seen_tokens, dtype=torch.int) < torch.tensor(end_index, dtype=torch.int),
+            past_seen_tokens,
+            end_index,
+        )
+        causal_mask_block = _create_causal_mask(
+            position_ids=position_ids, target_length=past_seen_tokens_end, start_index=past_seen_tokens_start
+        )
+
+        # Compute attention scores for the block
+        attn_weights_block = torch.matmul(query, K_block_states.transpose(2, 3)) * scaling
+        if attention_mask is not None:
+            attn_weights_block = torch.where(causal_mask_block, masked_tensor, attn_weights_block)
+
+        # Update Running row maximum
+        prev_max = current_max
+        current_max = torch.max(prev_max, attn_weights_block.max(dim=-1).values)
+        delta_max = prev_max - current_max
+
+        current_exp = torch.exp(
+            attn_weights_block - current_max.unsqueeze(-1)
+        )  # Subract current_max from each column of attn_weights_block
+
+        # update running denominator
+        prev_denominator = current_denominator
+        current_denominator = prev_denominator * torch.exp(delta_max) + current_exp.sum(axis=-1)
+
+        prob = current_exp / current_denominator.unsqueeze(-1)
+
+        prev_output = output
+        output = ((prev_denominator / current_denominator).unsqueeze(-1)) * prev_output * torch.exp(
+            delta_max.unsqueeze(-1)
+        ) + torch.matmul(prob, V_block_states)
+    attn_output = output.transpose(1, 2).contiguous()
+    attn_weights = None
+
+    return attn_output, attn_weights
+
+
 class QEffLlamaAttention(LlamaAttention):
     """Multi-headed attention from 'Attention Is All You Need' paper"""
 
@@ -136,6 +211,7 @@ def forward(
         batch_index: Optional[torch.LongTensor] = None,
         use_cache: bool = False,
         cache_position: Optional[torch.LongTensor] = None,
+        num_kv_blocks: Optional[torch.Tensor] = None,
         **kwargs,
     ) -> Tuple[torch.Tensor, Optional[torch.Tensor], Optional[Tuple[torch.Tensor]]]:
         input_shape = hidden_states.shape[:-1]
@@ -151,17 +227,29 @@ def forward(
         value_states = self.v_proj(hidden_states, **kwargs).view(hidden_shape).transpose(1, 2)
 
         kv_seq_len = past_key_value.get_seq_length(self.layer_idx, cache_position)
+        past_seen_tokens = past_key_value.get_seq_length() if past_key_value is not None else 0
         cos, sin = self.rotary_emb(value_states, seq_len=kv_seq_len)
         query_states, key_states = qeff_apply_rotary_pos_emb(query_states, key_states, cos, sin, position_ids)
 
         if past_key_value is not None:
-            cache_kwargs = {"batch_index": batch_index, "position_ids": position_ids}
-            if comp_ctx_lengths is not None:
-                attention_mask = attention_mask[:, :, :, : comp_ctx_lengths.shape[-1]]
-                cache_kwargs["CCL"] = attention_mask.shape[-1]
-            key_states, value_states = past_key_value.update(key_states, value_states, self.layer_idx, cache_kwargs)
-
-        attention_interface = eager_attention_forward
+            if num_kv_blocks is not None:
+                cache_kwargs = {
+                    "batch_index": batch_index,
+                    "position_ids": position_ids,
+                    "past_seen_tokens": past_seen_tokens,
+                }
+                past_key_value.write_only(key_states, value_states, self.layer_idx, cache_kwargs)
+            else:
+                cache_kwargs = {"batch_index": batch_index, "position_ids": position_ids}
+                if comp_ctx_lengths is not None:
+                    attention_mask = attention_mask[:, :, :, : comp_ctx_lengths.shape[-1]]
+                    cache_kwargs["CCL"] = attention_mask.shape[-1]
+                key_states, value_states = past_key_value.update(key_states, value_states, self.layer_idx, cache_kwargs)
+
+        if num_kv_blocks is not None:
+            attention_interface = eager_attention_forward_blockedKV
+        else:
+            attention_interface = eager_attention_forward
 
         attn_output, attn_weights = attention_interface(
             self,
@@ -170,6 +258,10 @@ def forward(
             value_states,
             attention_mask,
             scaling=self.scaling,
+            num_kv_blocks=num_kv_blocks,
+            cache_kwargs=cache_kwargs,
+            layer_idx=self.layer_idx,
+            past_key_value=past_key_value,
             **kwargs,
         )
         attn_output = attn_output.reshape(*input_shape, -1).contiguous()

QEfficient/transformers/models/modeling_auto.py

@@ -42,6 +42,7 @@
 from QEfficient.generation.vlm_generation import VisionLanguageGeneration
 from QEfficient.transformers.modeling_utils import DYNAMIC_SEQ_LEN_SUPPORTED_MODEL_ARCH
 from QEfficient.transformers.models.pytorch_transforms import (
+    BlockedKVAttentionTransform,
     CustomOpsTransform,
     KVCacheExternalModuleMapperTransform,
     KVCacheTransform,
@@ -2336,6 +2337,7 @@ def __init__(
             - **return_pdfs** (bool): If True, returns probability distributions along with sampled tokens.
               For Speculative Decoding Target Language Models, this is always True.
             - **max_top_k_ids** (int): Maximum number of top K tokens (<= vocab size) to consider during sampling.
+            - **num_kv_blocks** (int): Number of K/V blocks for BlockedKV attention implementation.
         **kwargs :
             Additional keyword arguments passed to the base class constructor.
 
@@ -2384,6 +2386,9 @@ def __init__(
         if self.is_tlm:
             self.model.qaic_config["return_pdfs"] = True
 
+        if self.model.qaic_config is not None and self.model.qaic_config.get("num_kv_blocks", None) is not None:
+            BlockedKVAttentionTransform.apply(model, num_kv_blocks=self.model.qaic_config.get("num_kv_blocks"))
+
     @property
     def model_name(self) -> str:
         """