[WIP] TPU V1 Support Refactored (#13049)

tests/entrypoints/llm/test_accuracy.py

@@ -21,10 +21,13 @@ RTOL = 0.03
 EXPECTED_VALUE = 0.58
 
 
-def run_test():
+def run_test(more_args=None):
     """Run the end to end accuracy test."""
 
-    model_args = f"pretrained={MODEL_NAME},max_model_len=2048"
+    model_args = f"pretrained={MODEL_NAME},max_model_len=4096"
+
+    if more_args is not None:
+        model_args = "{},{}".format(model_args, more_args)
 
     results = lm_eval.simple_evaluate(
         model="vllm",
@@ -39,14 +42,21 @@ def run_test():
             ), f"Expected: {EXPECTED_VALUE} |  Measured: {measured_value}"
 
 
-@pytest.mark.skipif(not current_platform.is_cuda(),
-                    reason="V1 is currently only supported on CUDA.")
+@pytest.mark.skipif(not current_platform.is_cuda()
+                    and not current_platform.is_tpu(),
+                    reason="V1 is currently only supported on CUDA and TPU")
 def test_lm_eval_accuracy_v1_engine(monkeypatch):
     """Run with the V1 Engine."""
 
     with monkeypatch.context() as m:
         m.setenv("VLLM_USE_V1", "1")
-        run_test()
+
+        more_args = None
+        if current_platform.is_tpu():
+            # Limit compilation time for TPU V1
+            more_args = "max_num_seqs=64"
+
+        run_test(more_args)
 
 
 def test_lm_eval_accuracy_v0_engine(monkeypatch):

tests/entrypoints/openai/correctness/test_lmeval.py

@@ -21,7 +21,7 @@ TASK = "gsm8k"
 FILTER = "exact_match,strict-match"
 RTOL = 0.03
 EXPECTED_VALUE = 0.58
-DEFAULT_ARGS = ["--max-model-len", "2048", "--disable-log-requests"]
+DEFAULT_ARGS = ["--max-model-len", "4096", "--disable-log-requests"]
 MORE_ARGS_LIST = [
     [],  # Default
     ["--enable-chunked-prefill"],  # Chunked
@@ -67,14 +67,21 @@ def run_test(more_args):
                 ), f"Expected: {EXPECTED_VALUE} |  Measured: {measured_value}"
 
 
-@pytest.mark.skipif(not current_platform.is_cuda(),
-                    reason="V1 currently only supported on CUDA")
+@pytest.mark.skipif(not current_platform.is_cuda()
+                    and not current_platform.is_tpu(),
+                    reason="V1 currently only supported on CUDA and TPU")
 def test_lm_eval_accuracy_v1_engine(monkeypatch):
     """Run with the V1 Engine."""
 
     with monkeypatch.context() as m:
         m.setenv("VLLM_USE_V1", "1")
-        run_test([])
+        more_args = []
+
+        # Limit compilation time for V1
+        if current_platform.is_tpu():
+            more_args = ["--max-num-seqs", "64"]
+
+        run_test(more_args)
 
 
 @pytest.mark.parametrize("more_args", MORE_ARGS_LIST)

vllm/platforms/interface.py

@@ -37,6 +37,7 @@ class _Backend(enum.Enum):
     TRITON_MLA = enum.auto()
     HPU_ATTN = enum.auto()
     PALLAS = enum.auto()
+    PALLAS_VLLM_V1 = enum.auto()
     IPEX = enum.auto()
     BLOCK_SPARSE_FLASH_ATTN = enum.auto()
     NO_ATTENTION = enum.auto()

vllm/platforms/tpu.py

@@ -4,6 +4,7 @@ from typing import TYPE_CHECKING, Optional
 
 import torch
 
+import vllm.envs as envs
 from vllm.logger import init_logger
 
 from .interface import Platform, PlatformEnum, _Backend
@@ -33,14 +34,20 @@ class TpuPlatform(Platform):
                              dtype: torch.dtype, kv_cache_dtype: Optional[str],
                              block_size: int, use_v1: bool,
                              use_mla: bool) -> str:
-        if selected_backend != _Backend.PALLAS:
+        if (selected_backend != _Backend.PALLAS
+                and selected_backend != _Backend.PALLAS_VLLM_V1):
             logger.info("Cannot use %s backend on TPU.", selected_backend)
-        logger.info("Using Pallas backend.")
-        return "vllm.attention.backends.pallas.PallasAttentionBackend"
+
+        if use_v1:
+            logger.info("Using Pallas V1 backend.")
+            return "vllm.v1.attention.backends.pallas.PallasAttentionBackend"
+        else:
+            logger.info("Using Pallas backend.")
+            return "vllm.attention.backends.pallas.PallasAttentionBackend"
 
     @classmethod
     def get_device_name(cls, device_id: int = 0) -> str:
-        raise NotImplementedError
+        return "tpu"
 
     @classmethod
     def get_device_total_memory(cls, device_id: int = 0) -> int:
@@ -48,7 +55,7 @@ class TpuPlatform(Platform):
 
     @classmethod
     def is_async_output_supported(cls, enforce_eager: Optional[bool]) -> bool:
-        return True
+        return not envs.VLLM_USE_V1
 
     @classmethod
     def inference_mode(cls):
@@ -63,11 +70,11 @@ class TpuPlatform(Platform):
             cache_config.block_size = 16
 
         compilation_config = vllm_config.compilation_config
-        if compilation_config.level == CompilationLevel.NO_COMPILATION:
-            # TPU does not support NO_COMPILATION
+
+        # TPU only supports DYNAMO_ONCE compilation level
+        if compilation_config.level != CompilationLevel.DYNAMO_ONCE:
+            logger.info("[TPU] Forcing DYNAMO_ONCE compilation level")
             compilation_config.level = CompilationLevel.DYNAMO_ONCE
-        assert compilation_config.level < CompilationLevel.PIECEWISE,\
-            "TPU does not support Inductor."
 
         if compilation_config.backend == "":
             compilation_config.backend = "openxla"
@@ -75,10 +82,6 @@ class TpuPlatform(Platform):
         assert vllm_config.speculative_config is None, \
             "TPU does not support speculative decoding"
 
-        assert not vllm_config.scheduler_config.chunked_prefill_enabled, (
-            "Chunked prefill is not yet supported for TPU backend")
-        assert not vllm_config.speculative_config, (
-            "Speculative decoding is not yet supported for TPU backend")
         if vllm_config.model_config.dtype in (torch.float16, torch.float32):
             logger.warning(
                 "The TPU backend currently does not support %s. "
@@ -88,8 +91,27 @@ class TpuPlatform(Platform):
         parallel_config = vllm_config.parallel_config
         scheduler_config = vllm_config.scheduler_config
         if parallel_config.worker_cls == "auto":
-            if scheduler_config.is_multi_step:
+            if envs.VLLM_USE_V1:
                 parallel_config.worker_cls = \
-                    "vllm.worker.multi_step_tpu_worker.MultiStepTPUWorker"
+                    "vllm.v1.worker.tpu_worker.TPUWorker"
             else:
-                parallel_config.worker_cls = "vllm.worker.tpu_worker.TPUWorker"
+                if scheduler_config.is_multi_step:
+                    parallel_config.worker_cls = \
+                        "vllm.worker.multi_step_tpu_worker.MultiStepTPUWorker"
+                else:
+                    parallel_config.worker_cls = \
+                        "vllm.worker.tpu_worker.TPUWorker"
+
+        # Adjust scheduler config for V1
+        # TODO: Add support for these
+        if envs.VLLM_USE_V1 and vllm_config.cache_config.enable_prefix_caching:
+            logger.warning("[V1][TPU] Disable prefix caching")
+            vllm_config.cache_config.enable_prefix_caching = False
+
+        assert not vllm_config.speculative_config, (
+            "Speculative decoding is not yet supported for TPU backend")
+
+    @classmethod
+    def is_pin_memory_available(cls):
+        logger.warning("Pin memory is not supported on TPU.")
+        return False

vllm/v1/attention/backends/pallas.py

+# SPDX-License-Identifier: Apache-2.0
+
+from dataclasses import dataclass
+from typing import Any, Dict, List, Optional, Tuple, Type
+
+import torch
+import torch_xla.experimental.custom_kernel  # Required to register custom ops.
+
+from vllm.attention.backends.abstract import (AttentionBackend, AttentionImpl,
+                                              AttentionLayer,
+                                              AttentionMetadata, AttentionType)
+from vllm.attention.backends.utils import CommonAttentionState
+
+
+class PallasAttentionBackend(AttentionBackend):
+
+    @staticmethod
+    def get_name() -> str:
+        return "PALLAS_VLLM_V1"
+
+    @staticmethod
+    def get_impl_cls() -> Type["PallasAttentionBackendImpl"]:
+        return PallasAttentionBackendImpl
+
+    @staticmethod
+    def get_metadata_cls() -> Type["PallasMetadata"]:
+        return PallasMetadata
+
+    @staticmethod
+    def get_state_cls() -> Type["CommonAttentionState"]:
+        return CommonAttentionState
+
+    @staticmethod
+    def get_kv_cache_shape(
+        num_blocks: int,
+        block_size: int,
+        num_kv_heads: int,
+        head_size: int,
+    ) -> Tuple[int, ...]:
+        return (num_kv_heads, num_blocks, block_size, head_size)
+
+    @staticmethod
+    def swap_blocks(
+        src_kv_cache: torch.Tensor,
+        dst_kv_cache: torch.Tensor,
+        src_to_dst: torch.Tensor,
+    ) -> None:
+        raise RuntimeError("swap_blocks is not used for the TPU backend.")
+
+    @torch.compile(backend="openxla")
+    @staticmethod
+    def copy_blocks(
+        kv_caches: List[Tuple[torch.Tensor, torch.Tensor]],
+        src_to_dists: Tuple[torch.Tensor, torch.Tensor],
+    ) -> None:
+        src_indices, dst_indices = src_to_dists
+        for k_cache, v_cache in kv_caches:
+            torch.ops.xla.dynamo_set_buffer_donor_(k_cache, True)
+            k_cache[:, dst_indices] = k_cache[:, src_indices]
+            torch.ops.xla.dynamo_set_buffer_donor_(v_cache, True)
+            v_cache[:, dst_indices] = v_cache[:, src_indices]
+
+
+@dataclass
+class PallasMetadata(AttentionMetadata):
+
+    # Currently, input sequences can only contain all prefills
+    # or all decoding.
+    block_tables: Optional[torch.Tensor] = None
+    context_lens: Optional[torch.Tensor] = None
+    effective_query_lens: Optional[torch.Tensor] = None
+
+    @property
+    def prefill_metadata(self) -> Optional["PallasMetadata"]:
+        if self.num_prefills == 0:
+            return None
+
+        assert self.num_decode_tokens == 0
+        return self
+
+    @property
+    def decode_metadata(self) -> Optional["PallasMetadata"]:
+        if self.num_decode_tokens == 0:
+            return None
+
+        assert self.num_prefills == 0
+        assert self.num_prefill_tokens == 0
+        assert self.block_tables is not None
+        assert self.context_lens is not None
+        return self
+
+
+class PallasAttentionBackendImpl(AttentionImpl):
+
+    def __init__(
+        self,
+        num_heads: int,
+        head_size: int,
+        scale: float,
+        num_kv_heads: int,
+        alibi_slopes: Optional[List[float]],
+        sliding_window: Optional[int],
+        kv_cache_dtype: str,
+        blocksparse_params: Optional[Dict[str, Any]] = None,
+        logits_soft_cap: Optional[float] = None,
+        attn_type: str = AttentionType.DECODER,
+    ) -> None:
+        self.num_heads = num_heads
+        self.head_size = head_size
+        self.scale = float(scale)
+        self.num_kv_heads = num_heads if num_kv_heads is None else num_kv_heads
+
+        assert self.num_heads % self.num_kv_heads == 0
+        self.num_queries_per_kv = self.num_heads // self.num_kv_heads
+        if head_size % 128 != 0:
+            raise NotImplementedError("Head size must be a multiple of 128.")
+        if alibi_slopes is not None:
+            raise NotImplementedError("Alibi slopes is not supported.")
+        if sliding_window is not None:
+            raise NotImplementedError("Sliding window is not supported.")
+        if kv_cache_dtype != "auto":
+            raise NotImplementedError("FP8 KV cache dtype is not supported.")
+        if blocksparse_params is not None:
+            raise NotImplementedError("Blocksparse is not supported.")
+        if logits_soft_cap is not None:
+            raise NotImplementedError(
+                "Attention logits soft-capping is not supported.")
+
+        if torch_xla.tpu.version() < 4:
+            raise NotImplementedError("TPU version must be 4 or higher.")
+
+        self.megacore_mode = None
+        tpu_env = torch_xla.tpu.get_tpu_env()
+        tpu_type = (tpu_env.get("ACCELERATOR_TYPE", None)
+                    or tpu_env.get("TYPE", None)
+                    or tpu_env.get("TPU_ACCELERATOR_TYPE", None))
+        assert tpu_type is not None
+        tpu_type = tpu_type.lower()
+
+        if (("lite" not in tpu_type) and ("v6" not in tpu_type)):
+            if self.num_kv_heads % 2 == 0:
+                self.megacore_mode = "kv_head"
+            else:
+                # NOTE(woosuk): If the batch size is not a multiple of 2, the
+                # megacore mode will be None.
+                self.megacore_mode = "batch"
+
+        if attn_type != AttentionType.DECODER:
+            raise NotImplementedError("Encoder self-attention and "
+                                      "encoder/decoder cross-attention "
+                                      "are not implemented for "
+                                      "PallasAttentionBackendImpl")
+
+    def forward(
+        self,
+        layer: AttentionLayer,
+        query: torch.Tensor,
+        key: torch.Tensor,
+        value: torch.Tensor,
+        kv_cache: Tuple[torch.Tensor, torch.Tensor],
+        attn_metadata: PallasMetadata,
+        output: Optional[torch.Tensor] = None,
+    ) -> torch.Tensor:
+        """Forward pass with Pallas attention.
+
+        Args:
+            query: shape = [batch_size, seq_len, num_heads * head_size]
+            key: shape = [batch_size, seq_len, num_kv_heads * head_size]
+            value: shape = [batch_size, seq_len, num_kv_heads * head_size]
+            kv_cache[0] = [num_kv_heads, num_blocks, block_size, head_size]
+            kv_cache[1] = [num_kv_heads, num_blocks, block_size, head_size]
+                NOTE: kv_cache[0] and kv_cache[1] will be an empty tensor 
+                with shape [0] for profiling run.
+            attn_metadata: Metadata for attention.
+        Returns:
+            shape = [batch_size, seq_len, num_heads * head_size]
+        """
+
+        if attn_metadata is None:
+            if output is None:
+                output = torch.ones_like(query)
+            return output
+
+        assert layer._k_scale_float == 1.0 and layer._v_scale_float == 1.0
+        batch_size, seq_len, hidden_size = query.shape
+        query = query.view(batch_size, seq_len, self.num_heads, self.head_size)
+        key = key.view(batch_size, seq_len, self.num_kv_heads, self.head_size)
+        value = value.view(batch_size, seq_len, self.num_kv_heads,
+                           self.head_size)
+
+        if kv_cache[0].numel() > 0:
+            slot_mapping = attn_metadata.slot_mapping
+            key_cache, value_cache = kv_cache
+            write_to_kv_cache(key, value, key_cache, value_cache, slot_mapping)
+
+        query = query * self.scale
+        if attn_metadata.num_prefills > 0:
+            if attn_metadata.block_tables is None:
+                # Prefill without paged KV cache.
+                assert seq_len % 16 == 0, (
+                    "Pallas FlashAttention kernel requires seq_len to be a "
+                    f"multiple of 16 but got {seq_len}")
+
+                # Handle GQA/MQA.
+                if self.num_kv_heads != self.num_heads:
+                    key = key.repeat_interleave(self.num_queries_per_kv,
+                                                dim=-2)
+                    key = key.view(batch_size, seq_len, self.num_heads,
+                                   self.head_size)
+                    value = value.repeat_interleave(self.num_queries_per_kv,
+                                                    dim=-2)
+                    value = value.view(batch_size, seq_len, self.num_heads,
+                                       self.head_size)
+                # FlashAttention kernel requires the input shape to be
+                # [batch_size, num_heads, seq_len, d_model]
+                # while the input is [batch_size, seq_len, num_heads, d_model].
+                # Permute the input to match the required format.
+                output = torch.ops.xla.flash_attention(
+                    query.permute(0, 2, 1, 3),
+                    key.permute(0, 2, 1, 3),
+                    value.permute(0, 2, 1, 3),
+                    True,
+                )
+                output = output.permute(0, 2, 1, 3)
+            else:
+                # Prefill with paged KV cache.
+                # TODO(woosuk): Tune the below knobs.
+                num_kv_pages_per_compute_block = 16
+                num_queries_per_compute_block = 16
+                assert seq_len % num_queries_per_compute_block == 0
+                output = torch.ops.xla.multi_queries_paged_attention(
+                    query,
+                    key_cache,
+                    value_cache,
+                    attn_metadata.context_lens,
+                    attn_metadata.block_tables,
+                    attn_metadata.effective_query_lens,
+                    num_kv_pages_per_compute_block,
+                    num_queries_per_compute_block,
+                    use_kernel=True,
+                )
+        else:
+            # Decoding run.
+            assert kv_cache[0].numel() > 0
+            query = query.squeeze(dim=1)
+            pages_per_compute_block = 16  # TODO(woosuk): Tune this value.
+
+            assert attn_metadata.block_tables is not None
+            assert attn_metadata.context_lens is not None
+            # NOTE(woosuk): The PagedAttention Pallas kernel stores the entire
+            # block table in SMEM. Therefore, if the block table is too large,
+            # the kernel compilation will fail. To avoid this, we split the
+            # batch dimension into smaller chunks and run the kernel multiple
+            # times.
+            MAX_SMEM_USAGE = 512 * 1024
+            size_per_seq = 4 * attn_metadata.block_tables.shape[1]
+            max_num_seq = MAX_SMEM_USAGE // size_per_seq
+
+            if batch_size <= max_num_seq:
+                output = paged_attention(
+                    query,
+                    key_cache,
+                    value_cache,
+                    attn_metadata.context_lens,
+                    attn_metadata.block_tables,
+                    pages_per_compute_block,
+                    self.megacore_mode,
+                )
+            else:
+                chunk_size = max_num_seq
+                # Make sure the chunk size is a multiple of 2.
+                chunk_size = chunk_size // 2 * 2
+                num_chunks = (batch_size + chunk_size - 1) // chunk_size
+
+                output = torch.empty_like(query)
+                for chunk_idx in range(num_chunks):
+                    chunk_start = chunk_idx * chunk_size
+                    chunk_end = chunk_start + chunk_size
+                    # NOTE(woosuk): We skip this line because it causes Dynamo
+                    # compilation error. Instead, we rely on the slice operation
+                    # to handle the out-of-bound case.
+                    # chunk_end = min(chunk_end, batch_size)
+                    chunk_output = paged_attention(
+                        query[chunk_start:chunk_end],
+                        key_cache,
+                        value_cache,
+                        attn_metadata.context_lens[chunk_start:chunk_end],
+                        attn_metadata.block_tables[chunk_start:chunk_end],
+                        pages_per_compute_block,
+                        self.megacore_mode,
+                    )
+                    output[chunk_start:chunk_end] = chunk_output
+
+        # Reshape the output tensor.
+        return output.reshape(batch_size, seq_len, hidden_size)
+
+
+def write_to_kv_cache(
+    key: torch.Tensor,
+    value: torch.Tensor,
+    key_cache: torch.Tensor,
+    value_cache: torch.Tensor,
+    slot_mapping: torch.Tensor,
+) -> None:
+    torch.ops.xla.dynamo_set_buffer_donor_(key_cache, True)
+    torch.ops.xla.dynamo_set_buffer_donor_(value_cache, True)
+
+    key = key.flatten(0, 2)
+    value = value.flatten(0, 2)
+    key_cache = key_cache.flatten(0, 2)
+    value_cache = value_cache.flatten(0, 2)
+    key_cache.index_copy_(0, slot_mapping, key)
+    value_cache.index_copy_(0, slot_mapping, value)
+
+
+def paged_attention(
+    query: torch.Tensor,
+    key_cache: torch.Tensor,
+    value_cache: torch.Tensor,
+    context_lens: torch.Tensor,
+    block_tables: torch.Tensor,
+    pages_per_compute_block: int,
+    megacore_mode: Optional[str],
+) -> torch.Tensor:
+    batch_size = query.shape[0]
+    if megacore_mode == "batch" and batch_size % 2 != 0:
+        megacore_mode = None
+    else:
+        megacore_mode = megacore_mode
+
+    # NOTE(woosuk): A temporary workaround to avoid the error:
+    # "xla::paged_attention() Expected a value of type 'str' for
+    # argument 'megacore_mode' but instead found type 'NoneType'."
+    if megacore_mode is not None:
+        output = torch.ops.xla.paged_attention(
+            query,
+            key_cache,
+            value_cache,
+            context_lens,
+            block_tables,
+            pages_per_compute_block,
+            megacore_mode=megacore_mode,
+        )
+    else:
+        output = torch.ops.xla.paged_attention(
+            query,
+            key_cache,
+            value_cache,
+            context_lens,
+            block_tables,
+            pages_per_compute_block,
+        )
+    return output

vllm/v1/worker/block_table.py

@@ -61,6 +61,14 @@ class BlockTable:
             src, :num_blocks]
         self.num_blocks_per_row[tgt] = num_blocks
 
+    def swap_row(self, src: int, tgt: int) -> None:
+        num_blocks_src = self.num_blocks_per_row[src]
+        num_blocks_tgt = self.num_blocks_per_row[tgt]
+        self.num_blocks_per_row[src] = num_blocks_tgt
+        self.num_blocks_per_row[tgt] = num_blocks_src
+
+        self.block_table_np[[src, tgt]] = self.block_table_np[[tgt, src]]
+
     def commit(self, num_reqs: int) -> None:
         self.block_table[:num_reqs].copy_(self.block_table_cpu[:num_reqs],
                                           non_blocking=True)

vllm/v1/worker/tpu_worker.py

+# SPDX-License-Identifier: Apache-2.0
+"""A TPU worker class."""
+import os
+from typing import Dict, List, Optional
+
+import torch
+import torch.distributed
+import torch.nn as nn
+import torch_xla.core.xla_model as xm
+import torch_xla.runtime as xr
+
+import vllm.envs as envs
+from vllm.config import ParallelConfig, VllmConfig
+from vllm.distributed import (ensure_model_parallel_initialized,
+                              init_distributed_environment)
+from vllm.logger import init_logger
+from vllm.model_executor import set_random_seed
+from vllm.utils import STR_DTYPE_TO_TORCH_DTYPE
+from vllm.v1.core.scheduler import SchedulerOutput
+from vllm.v1.kv_cache_interface import (FullAttentionSpec, KVCacheConfig,
+                                        KVCacheSpec)
+from vllm.v1.outputs import ModelRunnerOutput
+from vllm.v1.utils import bind_kv_cache
+from vllm.v1.worker.tpu_model_runner import ExecutionMode, TPUModelRunner
+
+logger = init_logger(__name__)
+
+
+class TPUWorker:
+
+    def __init__(
+        self,
+        vllm_config: VllmConfig,
+        local_rank: int,
+        rank: int,
+        distributed_init_method: str,
+        is_driver_worker: bool = False,
+    ):
+        self.vllm_config = vllm_config
+        self.model_config = vllm_config.model_config
+        self.cache_config = vllm_config.cache_config
+        self.lora_config = vllm_config.lora_config
+        self.load_config = vllm_config.load_config
+        self.parallel_config = vllm_config.parallel_config
+        self.scheduler_config = vllm_config.scheduler_config
+        self.device_config = vllm_config.device_config
+        self.speculative_config = vllm_config.speculative_config
+        self.prompt_adapter_config = vllm_config.prompt_adapter_config
+        self.observability_config = vllm_config.observability_config
+
+        self.parallel_config.rank = rank
+        self.local_rank = local_rank
+        self.rank = rank
+        self.distributed_init_method = distributed_init_method
+
+        if self.cache_config.cache_dtype == "auto":
+            self.cache_dtype = self.model_config.dtype
+        else:
+            self.cache_dtype = STR_DTYPE_TO_TORCH_DTYPE[
+                self.cache_config.cache_dtype]
+
+        if self.model_config.trust_remote_code:
+            # note: lazy import to avoid importing torch before initializing
+            from vllm.utils import init_cached_hf_modules
+            init_cached_hf_modules()
+
+    def init_device(self):
+        os.environ["PJRT_DEVICE"] = "TPU"
+        torch.set_grad_enabled(False)
+        torch.set_default_dtype(self.model_config.dtype)
+
+        # Initialize the distributed environment.
+        init_tpu_worker_distributed_environment(self.parallel_config,
+                                                self.rank,
+                                                self.distributed_init_method,
+                                                self.local_rank)
+
+        # Device initialization should happen after initializing
+        # the distributed runtime.
+        self.device = xm.xla_device()
+        self.device_config.device = self.device
+
+        # Set random seed.
+        set_random_seed(self.model_config.seed)
+        xm.set_rng_state(self.model_config.seed, self.device)
+
+        # Increase the cache size limit, which is the maximum number of
+        # dynamo graphs that can be compiled.
+        # NOTE(woosuk): Usually, we compile 10-15 graphs for prefill and
+        # 30-40 graphs for decode. 128 is an arbitrary safe number.
+        torch._dynamo.config.cache_size_limit = 128
+        # Use persistent cache to avoid XLA recompilation.
+        # NOTE(woosuk): Set per-rank cache path since different ranks
+        # can have slightly different XLA graphs.
+        world_size = self.parallel_config.world_size
+        rank = xr.global_ordinal()
+        per_rank_path = os.path.join(envs.VLLM_XLA_CACHE_PATH,
+                                     f"tp{world_size}_rank{rank}")
+        xr.initialize_cache(per_rank_path, readonly=False)
+
+        # Init ModelRunner here, so that we have access to self.device.
+        self.model_runner = TPUModelRunner(self.vllm_config, self.device)
+
+    def determine_available_memory(self) -> int:
+        kv_caches: Dict[str, torch.Tensor] = {}
+        kv_cache_spec = self.model_runner.get_kv_cache_spec()
+        for layer_name, layer_spec in kv_cache_spec.items():
+            if isinstance(layer_spec, FullAttentionSpec):
+                dtype = layer_spec.dtype
+
+                # Use an empty tensor instead of `None`` to force Dynamo to pass
+                # it by reference, rather by specializing on the value ``None``.
+                tpu_k_cache = torch.tensor([], dtype=dtype, device=self.device)
+                tpu_v_cache = torch.tensor([], dtype=dtype, device=self.device)
+
+                kv_caches[layer_name] = (tpu_k_cache, tpu_v_cache)
+            else:
+                raise NotImplementedError
+
+        runner_kv_caches: List[torch.Tensor] = []
+        bind_kv_cache(
+            kv_caches,
+            self.vllm_config.compilation_config.static_forward_context,
+            runner_kv_caches)
+
+        self.model_runner.dummy_run(
+            runner_kv_caches,
+            num_tokens=1,
+            seq_len=self.scheduler_config.max_num_batched_tokens,
+            exec_mode=ExecutionMode.PREFILL,
+        )
+
+        # Synchronize before measuring the memory usage.
+        xm.wait_device_ops()
+
+        # Get the maximum amount of memory used by the model weights and
+        # intermediate activations.
+        m = xm.get_memory_info(self.device)
+        total_memory_size = m["bytes_limit"]
+        profiled = m["peak_bytes_used"]  # Weights + intermediate activations.
+
+        # Calculate the TPU KV cache size based on profiling.
+        usable_memory_size = int(total_memory_size *
+                                 self.cache_config.gpu_memory_utilization)
+        tpu_kv_cache_bytes = max(usable_memory_size - profiled, 0)
+
+        return int(tpu_kv_cache_bytes)
+
+    def execute_model(
+        self,
+        scheduler_output: "SchedulerOutput",
+    ) -> Optional[ModelRunnerOutput]:
+        output = self.model_runner.execute_model(scheduler_output)
+        return output if self.rank == 0 else None
+
+    def load_model(self) -> None:
+        self.model_runner.load_model()
+
+    def compile_or_warm_up_model(self) -> None:
+        if not self.model_config.enforce_eager:
+            self.model_runner.capture_model()
+
+        # Reset the seed to ensure that the random state is not affected by
+        # the model initialization and profiling.
+        set_random_seed(self.model_config.seed)
+
+    def get_model(self) -> nn.Module:
+        return self.model_runner.get_model()
+
+    def get_kv_cache_spec(self) -> KVCacheSpec:
+        return self.model_runner.get_kv_cache_spec()
+
+    def initialize_cache(self, kv_cache_configs: List[KVCacheConfig]) -> None:
+        """Allocate GPU KV cache with the specified kv_cache_config."""
+        kv_cache_config = kv_cache_configs[self.rank]
+        self.model_runner.initialize_kv_cache(kv_cache_config)
+
+    def check_health(self) -> None:
+        # worker will always be healthy as long as it's running.
+        return
+
+
+def init_tpu_worker_distributed_environment(
+    parallel_config: ParallelConfig,
+    rank: int,
+    distributed_init_method: Optional[str] = None,
+    local_rank: int = -1,
+) -> None:
+    """Initialize the distributed environment."""
+
+    # NOTE(woosuk): This is just to initialize the TP group and broadcast
+    # the input objects on CPU. The all-reduce and all-gather ops on TPU
+    # are invoked by `xm.all_reduce` and `xm.all_gather` which use their
+    # own context.
+    init_distributed_environment(
+        world_size=parallel_config.world_size,
+        rank=rank,
+        local_rank=local_rank,
+        distributed_init_method=distributed_init_method,
+        backend="gloo",
+    )
+    ensure_model_parallel_initialized(parallel_config.tensor_parallel_size,
+                                      parallel_config.pipeline_parallel_size)