Optimize speculative decoding PVC memory usage (intel-analytics#10329)

* optimize memory

* update

* update

* update

* support other models

* update

* fix style

python/llm/src/bigdl/llm/transformers/speculative.py

@@ -24,8 +24,8 @@
 import os
 import copy
 import logging
-import warnings
-import inspect
+import transformers
+from packaging import version
 from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Tuple, Union
 from transformers import top_k_top_p_filtering, GenerationConfig, \
     LogitsProcessorList, StoppingCriteriaList
@@ -367,6 +367,55 @@ def _update_past_key_values_storage_cpu(self, past_key_values, past_key_values_s
                     delta_past_value.to(torch.float32)
 
 
+def _check_and_extend_kv_cache(past_key_values, max_step_draft, kv_alloc_block_len=256,
+                               model_type="llama"):
+    from bigdl.llm.transformers.models.utils import is_enough_kv_cache_room_4_31, \
+        extend_kv_cache
+    enough_kv_room = True
+    if model_type not in ["chatglm", "qwen", "baichuan", "llama", "mistral",
+                          "gptj", "opt"]:
+        return past_key_values, False
+    cache_k = past_key_values[0][0]
+    if model_type == "chatglm":
+        cache_k = cache_k.permute(1, 2, 0, 3)
+    elif model_type == "qwen":
+        cache_k = cache_k.transpose(1, 2)
+
+    enough_kv_room = is_enough_kv_cache_room_4_31(past_key_value=(cache_k, None),
+                                                  seq_len=max_step_draft)
+    bsz, num_heads, current_seq_len, head_dim = cache_k.shape
+    device = past_key_values[0][0].device
+    if not enough_kv_room:
+        past_key_values = list(past_key_values)
+        for i in range(len(past_key_values)):
+            cache_k = past_key_values[i][0]
+            cache_v = past_key_values[i][1]
+            if model_type == "chatglm":
+                cache_k = cache_k.permute(1, 2, 0, 3)
+                cache_v = cache_v.permute(1, 2, 0, 3)
+            elif model_type == "qwen":
+                cache_k = cache_k.transpose(1, 2)
+                cache_v = cache_v.transpose(1, 2)
+            new_cache_k, new_cache_v = extend_kv_cache(
+                bsz,
+                num_heads,  # Support GQA
+                head_dim,
+                cache_k.size(2),
+                current_seq_len + max_step_draft + kv_alloc_block_len,
+                dtype=cache_v.dtype,
+                device=device)
+            new_cache_k[:] = cache_k
+            new_cache_v[:] = cache_v
+            if model_type == "chatglm":
+                past_key_values[i] = (new_cache_k.permute(2, 0, 1, 3),
+                                      new_cache_v.permute(2, 0, 1, 3))
+            elif model_type == "qwen":
+                past_key_values[i] = (new_cache_k.transpose(1, 2), new_cache_v.transpose(1, 2))
+            else:
+                past_key_values[i] = (new_cache_k, new_cache_v)
+    return past_key_values, not enough_kv_room
+
+
 @torch.no_grad()
 def speculative_generate(self,
                          inputs: Optional[torch.Tensor] = None,
@@ -504,6 +553,9 @@ def speculative_generate(self,
 
     self.clear_benchmarks()
 
+    if self.device.type == 'xpu':
+        torch.xpu.empty_cache()
+
     # Example:
     # Target model forward for the first token
     # Step 1. target_model(prompt) -> a
@@ -562,6 +614,10 @@ def speculative_generate(self,
                                                        past_key_values_storage,  _enable_ipex)
                 original_draft_past_key_values = draft_past_key_values
             else:
+                past_key_values, extend_kv = _check_and_extend_kv_cache(past_key_values,
+                                                                        max_step_draft,
+                                                                        max_new_tokens - step + 40,
+                                                                        self.config.model_type)
                 draft_past_key_values = past_key_values
             draft_generate_ids[:, 0] = current_input_ids
             draft_prob_list = []
@@ -742,6 +798,8 @@ def speculative_generate(self,
                 output_ids = greedy(logits)
             if self.device.type == 'xpu':
                 torch.xpu.synchronize()
+                if extend_kv:
+                    torch.xpu.empty_cache()
             toc = time.time()
             self.verify_time.append(toc - tic)
             self.generate_time.append(self.draft_time[-1] + self.verify_time[-1])