Sync from v0.13

vllm/v1/kv_offload/backends/cpu.py

@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+import ctypes
+from collections.abc import Iterable
+
+from vllm.v1.core.kv_cache_utils import BlockHash
+from vllm.v1.kv_offload.abstract import LoadStoreSpec
+from vllm.v1.kv_offload.backend import Backend, BlockStatus
+from vllm.v1.kv_offload.mediums import CPULoadStoreSpec
+
+
+class CPUBlockStatus(BlockStatus):
+    _fields_ = BlockStatus._fields_ + [("block_id", ctypes.c_int64)]  # type: ignore
+
+    def __init__(self, block_id: int):
+        super().__init__()
+        self.block_id = block_id
+
+
+class CPUBackend(Backend):
+    def __init__(self, block_size: int, num_blocks: int):
+        super().__init__(block_size=block_size, medium=CPULoadStoreSpec.medium())
+
+        self.num_blocks: int = num_blocks
+        self.num_allocated_blocks: int = 0
+        self.allocated_blocks_free_list: list[int] = []
+
+    def get_num_free_blocks(self):
+        return (
+            len(self.allocated_blocks_free_list)
+            + self.num_blocks
+            - self.num_allocated_blocks
+        )
+
+    def allocate_blocks(self, block_hashes: list[BlockHash]) -> list[BlockStatus]:
+        num_fresh_blocks = min(
+            len(block_hashes), self.num_blocks - self.num_allocated_blocks
+        )
+        num_reused_blocks = len(block_hashes) - num_fresh_blocks
+        assert len(self.allocated_blocks_free_list) >= num_reused_blocks
+
+        # allocate fresh blocks
+        blocks: list[BlockStatus] = []
+        for _ in range(num_fresh_blocks):
+            blocks.append(CPUBlockStatus(self.num_allocated_blocks))
+            self.num_allocated_blocks += 1
+
+        # allocate reused blocks
+        for _ in range(num_reused_blocks):
+            block_id = self.allocated_blocks_free_list.pop()
+            blocks.append(CPUBlockStatus(block_id))
+
+        return blocks
+
+    def free(self, block: BlockStatus):
+        assert isinstance(block, CPUBlockStatus)
+        self.allocated_blocks_free_list.append(block.block_id)
+
+    def get_load_store_spec(
+        self, block_hashes: Iterable[BlockHash], blocks: Iterable[BlockStatus]
+    ) -> LoadStoreSpec:
+        return CPULoadStoreSpec([block.block_id for block in blocks])