Hierarchical Caching supports MLA (#4009)

Signed-off-by: Changqi Lu <luchangqi.123@bytedance.com>
Co-authored-by: Zhiqiang Xie <xiezhq@stanford.edu>

python/sglang/srt/managers/cache_controller.py

@@ -22,10 +22,7 @@ from typing import List, Optional
 
 import torch
 
-from sglang.srt.mem_cache.memory_pool import (
-    MHATokenToKVPoolHost,
-    TokenToKVPoolAllocator,
-)
+from sglang.srt.mem_cache.memory_pool import HostKVCache, TokenToKVPoolAllocator
 
 logger = logging.getLogger(__name__)
 
@@ -151,7 +148,7 @@ class HiCacheController:
     def __init__(
         self,
         token_to_kv_pool_allocator: TokenToKVPoolAllocator,
-        mem_pool_host: MHATokenToKVPoolHost,
+        mem_pool_host: HostKVCache,
         load_cache_event: threading.Event = None,
         write_policy: str = "write_through_selective",
     ):

python/sglang/srt/mem_cache/hiradix_cache.py

@@ -8,7 +8,10 @@ import torch
 
 from sglang.srt.managers.cache_controller import HiCacheController
 from sglang.srt.mem_cache.memory_pool import (
+    MHATokenToKVPool,
     MHATokenToKVPoolHost,
+    MLATokenToKVPool,
+    MLATokenToKVPoolHost,
     ReqToTokenPool,
     TokenToKVPoolAllocator,
 )
@@ -31,9 +34,14 @@ class HiRadixCache(RadixCache):
             raise ValueError(
                 "Page size larger than 1 is not yet supported in HiRadixCache."
             )
-        self.token_to_kv_pool_host = MHATokenToKVPoolHost(
-            token_to_kv_pool_allocator.get_kvcache()
-        )
+        self.kv_cache = token_to_kv_pool_allocator.get_kvcache()
+        if isinstance(self.kv_cache, MHATokenToKVPool):
+            self.token_to_kv_pool_host = MHATokenToKVPoolHost(self.kv_cache)
+        elif isinstance(self.kv_cache, MLATokenToKVPool):
+            self.token_to_kv_pool_host = MLATokenToKVPoolHost(self.kv_cache)
+        else:
+            raise ValueError(f"Only MHA and MLA supports swap kv_cache to host.")
+
         self.tp_group = tp_cache_group
         self.page_size = page_size
 
@@ -317,13 +325,11 @@ class HiRadixCache(RadixCache):
             prefix_len = _key_match(child.key, key)
             if prefix_len < len(child.key):
                 new_node = self._split_node(child.key, child, prefix_len)
-                self.inc_hit_count(new_node)
                 if not new_node.evicted:
                     value.append(new_node.value)
                 node = new_node
                 break
             else:
-                self.inc_hit_count(child)
                 if not child.evicted:
                     value.append(child.value)
                 node = child

python/sglang/srt/mem_cache/memory_pool.py

@@ -115,6 +115,21 @@ class KVCache(abc.ABC):
     ) -> None:
         raise NotImplementedError()
 
+    @abc.abstractmethod
+    def get_flat_data(self, indices):
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def transfer(self, indices, flat_data):
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def transfer_per_layer(self, indices, flat_data, layer_id):
+        raise NotImplementedError()
+
+    def register_layer_transfer_counter(self, layer_transfer_counter):
+        self.layer_transfer_counter = layer_transfer_counter
+
 
 class TokenToKVPoolAllocator:
     """An allocator managing the indices to kv cache data."""
@@ -275,9 +290,6 @@ class MHATokenToKVPool(KVCache):
             self.k_buffer[i][indices] = k_data[i]
             self.v_buffer[i][indices] = v_data[i]
 
-    def register_layer_transfer_counter(self, layer_transfer_counter):
-        self.layer_transfer_counter = layer_transfer_counter
-
     def transfer_per_layer(self, indices, flat_data, layer_id):
         # transfer prepared data from host to device
         flat_data = flat_data.to(device=self.device, non_blocking=False)
@@ -388,6 +400,8 @@ class MLATokenToKVPool(KVCache):
         else:
             self.store_dtype = dtype
         self.kv_lora_rank = kv_lora_rank
+        self.qk_rope_head_dim = qk_rope_head_dim
+        self.layer_num = layer_num
 
         memory_saver_adapter = TorchMemorySaverAdapter.create(
             enable=enable_memory_saver
@@ -404,12 +418,20 @@ class MLATokenToKVPool(KVCache):
                 for _ in range(layer_num)
             ]
 
+        self.layer_transfer_counter = None
+
     def get_key_buffer(self, layer_id: int):
+        if self.layer_transfer_counter is not None:
+            self.layer_transfer_counter.wait_until(layer_id)
+
         if self.store_dtype != self.dtype:
             return self.kv_buffer[layer_id].view(self.dtype)
         return self.kv_buffer[layer_id]
 
     def get_value_buffer(self, layer_id: int):
+        if self.layer_transfer_counter is not None:
+            self.layer_transfer_counter.wait_until(layer_id)
+
         if self.store_dtype != self.dtype:
             return self.kv_buffer[layer_id][..., : self.kv_lora_rank].view(self.dtype)
         return self.kv_buffer[layer_id][..., : self.kv_lora_rank]
@@ -432,6 +454,22 @@ class MLATokenToKVPool(KVCache):
         else:
             self.kv_buffer[layer_id][loc] = cache_k
 
+    def get_flat_data(self, indices):
+        # prepare a large chunk of contiguous data for efficient transfer
+        return torch.stack([self.kv_buffer[i][indices] for i in range(self.layer_num)])
+
+    @debug_timing
+    def transfer(self, indices, flat_data):
+        # transfer prepared data from host to device
+        flat_data = flat_data.to(device=self.device, non_blocking=False)
+        for i in range(self.layer_num):
+            self.kv_buffer[i][indices] = flat_data[i]
+
+    def transfer_per_layer(self, indices, flat_data, layer_id):
+        # transfer prepared data from host to device
+        flat_data = flat_data.to(device=self.device, non_blocking=False)
+        self.kv_buffer[layer_id][indices] = flat_data
+
 
 class DoubleSparseTokenToKVPool(KVCache):
     def __init__(
@@ -508,6 +546,15 @@ class DoubleSparseTokenToKVPool(KVCache):
         self.v_buffer[layer_id][loc] = cache_v
         self.label_buffer[layer_id][loc] = cache_label
 
+    def get_flat_data(self, indices):
+        pass
+
+    def transfer(self, indices, flat_data):
+        pass
+
+    def transfer_per_layer(self, indices, flat_data, layer_id):
+        pass
+
 
 class MemoryStateInt(IntEnum):
     IDLE = 0
@@ -526,7 +573,7 @@ def synchronized(func):
     return wrapper
 
 
-class MHATokenToKVPoolHost:
+class HostKVCache(abc.ABC):
 
     def __init__(
         self,
@@ -547,12 +594,7 @@ class MHATokenToKVPoolHost:
 
         self.size = int(device_pool.size * host_to_device_ratio)
         self.dtype = device_pool.store_dtype
-        self.head_num = device_pool.head_num
-        self.head_dim = device_pool.head_dim
-        self.layer_num = device_pool.layer_num
-        self.size_per_token = (
-            self.head_dim * self.head_num * self.layer_num * self.dtype.itemsize * 2
-        )
+        self.size_per_token = self.get_size_per_token()
 
         # Verify there is enough available host memory.
         host_mem = psutil.virtual_memory()
@@ -571,12 +613,7 @@ class MHATokenToKVPoolHost:
                 f"Allocating {requested_bytes / 1e9:.2f} GB host memory for hierarchical KV cache."
             )
 
-        self.kv_buffer = torch.zeros(
-            (2, self.layer_num, self.size, self.head_num, self.head_dim),
-            dtype=self.dtype,
-            device=self.device,
-            pin_memory=self.pin_memory,
-        )
+        self.kv_buffer = self.init_kv_buffer()
 
         # Initialize memory states and tracking structures.
         self.mem_state = torch.zeros(
@@ -588,21 +625,29 @@ class MHATokenToKVPoolHost:
         # A lock for synchronized operations on memory allocation and state transitions.
         self.lock = threading.RLock()
 
+    @abc.abstractmethod
+    def get_size_per_token(self):
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def init_kv_buffer(self):
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def transfer(self, indices, flat_data):
+        raise NotImplementedError()
+
+    @abc.abstractmethod
     def get_flat_data(self, indices):
-        return self.kv_buffer[:, :, indices]
+        raise NotImplementedError()
 
+    @abc.abstractmethod
     def get_flat_data_by_layer(self, indices, layer_id):
-        return self.kv_buffer[:, layer_id, indices]
+        raise NotImplementedError()
 
+    @abc.abstractmethod
     def assign_flat_data(self, indices, flat_data):
-        self.kv_buffer[:, :, indices] = flat_data
-
-    @debug_timing
-    def transfer(self, indices, flat_data):
-        # backup prepared data from device to host
-        self.kv_buffer[:, :, indices] = flat_data.to(
-            device=self.device, non_blocking=False
-        )
+        raise NotImplementedError()
 
     @synchronized
     def clear(self):
@@ -694,3 +739,92 @@ class MHATokenToKVPoolHost:
         self.free_slots = torch.concat([self.free_slots, indices])
         self.can_use_mem_size += len(indices)
         return len(indices)
+
+
+class MHATokenToKVPoolHost(HostKVCache):
+    def __init__(
+        self,
+        device_pool: MHATokenToKVPool,
+        host_to_device_ratio: float = 3.0,
+        pin_memory: bool = False,  # no need to use pin memory with the double buffering
+        device: str = "cpu",
+    ):
+        super().__init__(device_pool, host_to_device_ratio, pin_memory, device)
+
+    def get_size_per_token(self):
+        self.head_num = self.device_pool.head_num
+        self.head_dim = self.device_pool.head_dim
+        self.layer_num = self.device_pool.layer_num
+
+        return self.head_dim * self.head_num * self.layer_num * self.dtype.itemsize * 2
+
+    def init_kv_buffer(self):
+        return torch.empty(
+            (2, self.layer_num, self.size, self.head_num, self.head_dim),
+            dtype=self.dtype,
+            device=self.device,
+            pin_memory=self.pin_memory,
+        )
+
+    @debug_timing
+    def transfer(self, indices, flat_data):
+        # backup prepared data from device to host
+        self.kv_buffer[:, :, indices] = flat_data.to(
+            device=self.device, non_blocking=False
+        )
+
+    def get_flat_data(self, indices):
+        return self.kv_buffer[:, :, indices]
+
+    def get_flat_data_by_layer(self, indices, layer_id):
+        return self.kv_buffer[:, layer_id, indices]
+
+    def assign_flat_data(self, indices, flat_data):
+        self.kv_buffer[:, :, indices] = flat_data
+
+
+class MLATokenToKVPoolHost(HostKVCache):
+    def __init__(
+        self,
+        device_pool: MLATokenToKVPool,
+        host_to_device_ratio: float = 4.0,
+        pin_memory: bool = False,  # no need to use pin memory with the double buffering
+        device: str = "cpu",
+    ):
+        super().__init__(device_pool, host_to_device_ratio, pin_memory, device)
+
+    def get_size_per_token(self):
+        self.kv_lora_rank = self.device_pool.kv_lora_rank
+        self.qk_rope_head_dim = self.device_pool.qk_rope_head_dim
+        self.layer_num = self.device_pool.layer_num
+
+        return (self.kv_lora_rank + self.qk_rope_head_dim) * 1 * self.dtype.itemsize
+
+    def init_kv_buffer(self):
+        return torch.empty(
+            (
+                self.layer_num,
+                self.size,
+                1,
+                self.kv_lora_rank + self.qk_rope_head_dim,
+            ),
+            dtype=self.dtype,
+            device=self.device,
+            pin_memory=self.pin_memory,
+        )
+
+    @debug_timing
+    def transfer(self, indices, flat_data):
+        # backup prepared data from device to host
+        self.kv_buffer[:, indices] = flat_data.to(
+            device=self.device, non_blocking=False
+        )
+
+    def get_flat_data(self, indices):
+        return self.kv_buffer[:, indices]
+
+    def get_flat_data_by_layer(self, indices, layer_id):
+        return self.kv_buffer[layer_id, indices]
+
+    def assign_flat_data(self, indices, flat_data):
+        self.kv_buffer[:, indices] = flat_data

test/srt/test_hierarchical_mla.py

+import unittest
+from types import SimpleNamespace
+
+from sglang.srt.utils import kill_process_tree
+from sglang.test.run_eval import run_eval
+from sglang.test.test_utils import (
+    DEFAULT_MLA_MODEL_NAME_FOR_TEST,
+    DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
+    DEFAULT_URL_FOR_TEST,
+    popen_launch_server,
+)
+
+
+class TestHierarchicalMLA(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.model = DEFAULT_MLA_MODEL_NAME_FOR_TEST
+        cls.base_url = DEFAULT_URL_FOR_TEST
+        cls.process = popen_launch_server(
+            cls.model,
+            cls.base_url,
+            timeout=DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
+            other_args=["--trust-remote-code", "--enable-hierarchical-cache"],
+        )
+
+    @classmethod
+    def tearDownClass(cls):
+        kill_process_tree(cls.process.pid)
+
+    def test_mmlu(self):
+        args = SimpleNamespace(
+            base_url=self.base_url,
+            model=self.model,
+            eval_name="mmlu",
+            num_examples=64,
+            num_threads=32,
+        )
+
+        metrics = run_eval(args)
+        self.assertGreater(metrics["score"], 0.5)
+
+    def test_mgsm_en(self):
+        args = SimpleNamespace(
+            base_url=self.base_url,
+            model=self.model,
+            eval_name="mgsm_en",
+            num_examples=None,
+            num_threads=1024,
+        )
+
+        metrics = run_eval(args)
+        self.assertGreater(metrics["score"], 0.8)
+
+
+if __name__ == "__main__":
+    unittest.main()