257 lines
11 KiB
Python
257 lines
11 KiB
Python
# SPDX-License-Identifier: Apache-2.0
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"""A TPU worker class."""
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import os
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from typing import Optional
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import torch
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import torch.distributed
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import torch.nn as nn
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import torch_xla.core.xla_model as xm
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import torch_xla.debug.profiler as xp
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import torch_xla.runtime as xr
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import vllm.envs as envs
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from vllm.config import ParallelConfig, VllmConfig
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from vllm.distributed import (ensure_model_parallel_initialized,
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init_distributed_environment)
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from vllm.logger import init_logger
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from vllm.model_executor import set_random_seed
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from vllm.utils import STR_DTYPE_TO_TORCH_DTYPE
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from vllm.v1.core.sched.output import SchedulerOutput
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from vllm.v1.kv_cache_interface import (AttentionSpec, KVCacheConfig,
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KVCacheSpec)
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from vllm.v1.outputs import ModelRunnerOutput
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from vllm.v1.utils import bind_kv_cache
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from vllm.v1.worker.tpu_model_runner import TPUModelRunner
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logger = init_logger(__name__)
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class TPUWorker:
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def __init__(
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self,
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vllm_config: VllmConfig,
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local_rank: int,
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rank: int,
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distributed_init_method: str,
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is_driver_worker: bool = False,
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):
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self.is_driver_worker = is_driver_worker
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self.vllm_config = vllm_config
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self.model_config = vllm_config.model_config
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self.cache_config = vllm_config.cache_config
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self.lora_config = vllm_config.lora_config
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self.load_config = vllm_config.load_config
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self.parallel_config = vllm_config.parallel_config
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self.scheduler_config = vllm_config.scheduler_config
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self.device_config = vllm_config.device_config
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self.speculative_config = vllm_config.speculative_config
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self.prompt_adapter_config = vllm_config.prompt_adapter_config
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self.observability_config = vllm_config.observability_config
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self.parallel_config.rank = rank
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self.local_rank = local_rank
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self.rank = rank
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self.distributed_init_method = distributed_init_method
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if self.cache_config.cache_dtype == "auto":
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self.cache_dtype = self.model_config.dtype
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else:
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self.cache_dtype = STR_DTYPE_TO_TORCH_DTYPE[
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self.cache_config.cache_dtype]
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if self.model_config.trust_remote_code:
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# note: lazy import to avoid importing torch before initializing
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from vllm.utils import init_cached_hf_modules
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init_cached_hf_modules()
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# Delay profiler initialization to the start of the profiling.
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# This is because in vLLM V1, MP runtime is initialized before the
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# TPU Worker is initialized. The profiler server needs to start after
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# MP runtime is initialized.
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self.profiler = None
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self.profile_dir = None
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if envs.VLLM_TORCH_PROFILER_DIR and self.rank < 1:
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# For TPU, we can only have 1 active profiler session for 1 profiler
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# server. So we only profile on rank0.
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self.profile_dir = envs.VLLM_TORCH_PROFILER_DIR
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logger.info("Profiling enabled. Traces will be saved to: %s",
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self.profile_dir)
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if self.model_config.seed is None:
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self.model_config.seed = 0
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def init_device(self):
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os.environ["PJRT_DEVICE"] = "TPU"
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# Note: Currently the XLA compiler wrongly uses 2D ring strategy on 1D
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# ring, the xla tpu compiler flag
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# `xla_tpu_force_1d_allreduce_at_chunk_count` is a temporary solution to
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# fix this. It will be removed after the bug in XLA compiler is fixed.
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os.environ["LIBTPU_INIT_ARGS"] = (
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"--xla_tpu_force_1d_allreduce_at_chunk_count=1")
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torch.set_grad_enabled(False)
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torch.set_default_dtype(self.model_config.dtype)
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# Initialize the distributed environment.
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init_tpu_worker_distributed_environment(self.parallel_config,
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self.rank,
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self.distributed_init_method,
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self.local_rank)
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# Device initialization should happen after initializing
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# the distributed runtime.
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self.device = xm.xla_device()
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self.device_config.device = self.device
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# Set random seed.
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set_random_seed(self.model_config.seed)
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if self.model_config.seed is not None:
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xm.set_rng_state(self.model_config.seed, self.device)
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# Increase the cache size limit, which is the maximum number of
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# dynamo graphs that can be compiled.
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# TODO (NickLucche) On gsm we compile 80+ graphs.
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# Re-evaluate limit, with MM we may get close to this limit.
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torch._dynamo.config.cache_size_limit = 128
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# Use persistent cache to avoid XLA recompilation.
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# NOTE(woosuk): Set per-rank cache path since different ranks
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# can have slightly different XLA graphs.
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world_size = self.parallel_config.world_size
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rank = xr.global_ordinal()
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# The PyTorch/XLA compilation cache uses the Torch IR to generate keys.
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# Consequently, changes in optimization flags, which affect compilation
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# results, don't change the cache key. This can result in the wrong
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# compilation being used. To prevent this, disabling the XLA compilation
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# cache during development is recommended.We can disable it by
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# `export VLLM_XLA_CACHE_PATH=`
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if envs.VLLM_XLA_CACHE_PATH:
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per_rank_path = os.path.join(envs.VLLM_XLA_CACHE_PATH,
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f"tp{world_size}_rank{rank}")
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xr.initialize_cache(per_rank_path, readonly=False)
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# Init ModelRunner here, so that we have access to self.device.
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self.model_runner = TPUModelRunner(self.vllm_config, self.device)
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def determine_available_memory(self) -> int:
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kv_caches: dict[str, torch.Tensor] = {}
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kv_cache_spec = self.model_runner.get_kv_cache_spec()
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for layer_name, layer_spec in kv_cache_spec.items():
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if isinstance(layer_spec, AttentionSpec):
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dtype = layer_spec.dtype
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# Use an empty tensor instead of `None`` to force Dynamo to pass
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# it by reference, rather by specializing on the value ``None``.
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tpu_kv_cache = torch.tensor([],
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dtype=dtype,
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device=self.device)
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kv_caches[layer_name] = tpu_kv_cache
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else:
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raise NotImplementedError(
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f"Unsupported KV cache spec '{type(layer_spec)}'")
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runner_kv_caches: list[torch.Tensor] = []
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bind_kv_cache(
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kv_caches,
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self.vllm_config.compilation_config.static_forward_context,
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runner_kv_caches)
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# `max_num_tokens >= max_num_batched_tokens` due to padding.
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self.model_runner._dummy_run(self.model_runner.max_num_tokens)
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# Synchronize before measuring the memory usage.
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xm.wait_device_ops()
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# During the profiling run, the model runs without KV cache. After
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# the profiling run, the model always runs with KV cache. Here we clear
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# the dynamo cache and cached bytecode to ensure the model always has
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# one compiled bytecode. Having one FX graph/cached bytecode per
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# compiled model is required for `support_torch_compile` decorator to
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# skip dynamo guard.
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self.model_runner.reset_dynamo_cache()
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# Get the maximum amount of memory used by the model weights and
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# intermediate activations.
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m = xm.get_memory_info(self.device)
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total_memory_size = m["bytes_limit"]
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current_mem = m["bytes_used"]
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# Ideally we would use profiled = m["peak_bytes_used"] to
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# get weights + activations. But there is memory used during
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# compilation / weight loading that impacts the peak and
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# there is no way to reset peak memory in XLA, So we
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# use the heuristic of 2% of weights.
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profiled = current_mem * 1.02
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# Calculate the TPU KV cache size based on profiling.
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usable_memory_size = int(total_memory_size *
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self.cache_config.gpu_memory_utilization)
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tpu_kv_cache_bytes = max(usable_memory_size - profiled, 0)
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return int(tpu_kv_cache_bytes)
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def execute_model(
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self,
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scheduler_output: "SchedulerOutput",
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) -> Optional[ModelRunnerOutput]:
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output = self.model_runner.execute_model(scheduler_output)
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return output if self.is_driver_worker else None
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def profile(self, is_start: bool = True):
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if self.rank < 1:
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if self.profile_dir is None:
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raise RuntimeError("Profiler is not enabled.")
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if is_start:
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if self.profiler is None:
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self.profiler = xp.start_server(9012)
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xp.start_trace(self.profile_dir)
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else:
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xp.stop_trace()
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def load_model(self) -> None:
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self.model_runner.load_model()
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def compile_or_warm_up_model(self) -> None:
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if not self.model_config.enforce_eager:
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self.model_runner.capture_model()
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# Reset the seed to ensure that the random state is not affected by
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# the model initialization and profiling.
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set_random_seed(self.model_config.seed)
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def get_model(self) -> nn.Module:
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return self.model_runner.get_model()
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def get_kv_cache_spec(self) -> dict[str, KVCacheSpec]:
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return self.model_runner.get_kv_cache_spec()
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def initialize_from_config(self, kv_cache_config: KVCacheConfig) -> None:
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"""Allocate GPU KV cache with the specified kv_cache_config."""
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self.model_runner.initialize_kv_cache(kv_cache_config)
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def check_health(self) -> None:
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# worker will always be healthy as long as it's running.
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return
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def init_tpu_worker_distributed_environment(
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parallel_config: ParallelConfig,
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rank: int,
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distributed_init_method: Optional[str] = None,
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local_rank: int = -1,
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) -> None:
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"""Initialize the distributed environment."""
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# NOTE(woosuk): This is just to initialize the TP group and broadcast
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# the input objects on CPU. The all-reduce and all-gather ops on TPU
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# are invoked by `xm.all_reduce` and `xm.all_gather` which use their
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# own context.
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init_distributed_environment(
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world_size=parallel_config.world_size,
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rank=rank,
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local_rank=local_rank,
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distributed_init_method=distributed_init_method,
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backend="gloo",
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)
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ensure_model_parallel_initialized(parallel_config.tensor_parallel_size,
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parallel_config.pipeline_parallel_size)
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