vllm/vllm/v1/worker/ubatching.py
Wentao Ye b5d90f7400
[Bug] Fix DBO IMA issue for DeepEPHT (#27666)
Signed-off-by: yewentao256 <zhyanwentao@126.com>
2025-10-29 16:28:27 -04:00

232 lines
7.8 KiB
Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import threading
from typing import Optional
import torch
from vllm import forward_context
from vllm.forward_context import ForwardContext
from vllm.utils.torch_utils import current_stream
_THREAD_ID_TO_CONTEXT: dict = {}
_CURRENT_CONTEXTS: list[Optional["UBatchContext"]] = [None, None]
class UBatchContext:
"""
Context manager for micro-batching synchronization using threading events.
"""
def __init__(
self,
id: int,
comm_stream: torch.cuda.Stream,
compute_stream: torch.cuda.Stream,
forward_context: ForwardContext,
ready_barrier: threading.Barrier,
cpu_wait_event: threading.Event,
cpu_signal_event: threading.Event,
gpu_comm_done_event: torch.cuda.Event,
gpu_compute_done_event: torch.cuda.Event,
schedule: str = "default",
):
self.id = id
self.comm_stream = comm_stream
self.compute_stream = compute_stream
self.forward_context = forward_context
self.ready_barrier = ready_barrier
self.cpu_wait_event = cpu_wait_event
self.cpu_signal_event = cpu_signal_event
self.current_stream = compute_stream
self.gpu_comm_done_event = gpu_comm_done_event
self.gpu_compute_done_event = gpu_compute_done_event
self.schedule = schedule
self.recv_hook = None
def __enter__(self):
global _CURRENT_CONTEXTS, _THREAD_ID_TO_CONTEXT
_THREAD_ID_TO_CONTEXT[threading.get_ident()] = self.id
_CURRENT_CONTEXTS[self.id] = self
self.ready_barrier.wait()
self.cpu_wait_event.wait()
self.cpu_wait_event.clear()
self._restore_context()
# Assume we want to start on the compute stream
self.update_stream(self.compute_stream)
return self
def __exit__(self, exc_type, exc_val, exc_tb):
global _CURRENT_CONTEXTS, _THREAD_ID_TO_CONTEXT
_CURRENT_CONTEXTS[self.id] = None
del _THREAD_ID_TO_CONTEXT[threading.get_ident()]
self.maybe_run_recv_hook()
self.cpu_signal_event.set()
self.cpu_wait_event.clear()
return False
def _restore_context(self):
forward_context._forward_context = self.forward_context
def update_stream(self, stream):
self.current_stream = stream
if current_stream() != self.current_stream:
torch.cuda.set_stream(self.current_stream)
def _signal_comm_done(self):
self.gpu_comm_done_event.record(self.comm_stream)
def _signal_compute_done(self):
self.gpu_compute_done_event.record(self.compute_stream)
def _wait_compute_done(self):
self.comm_stream.wait_event(self.gpu_compute_done_event)
def _wait_comm_done(self):
self.compute_stream.wait_event(self.gpu_comm_done_event)
def _cpu_yield(self):
# It is critical for correctness that only one thread is running
# at a time. These asserts just make sure that this is the only
# thread running before waking the other one up and going to sleep
assert forward_context._forward_context == self.forward_context
assert current_stream() == self.current_stream
assert not self.cpu_wait_event.is_set()
self.cpu_signal_event.set()
self.cpu_wait_event.wait()
self.cpu_wait_event.clear()
self._restore_context()
def switch_to_comm(self):
self.update_stream(self.comm_stream)
def switch_to_compute(self):
self.update_stream(self.compute_stream)
def switch_to_comm_sync(self):
self._signal_compute_done()
self.update_stream(self.comm_stream)
self._wait_compute_done()
def switch_to_compute_sync(self):
self._signal_comm_done()
self.update_stream(self.compute_stream)
self._wait_comm_done()
def maybe_run_recv_hook(self):
if self.recv_hook is not None:
self.recv_hook()
self.recv_hook = None
def yield_(self):
self.current_stream = current_stream()
self._cpu_yield()
self.update_stream(self.current_stream)
def yield_and_switch_from_compute_to_comm(self):
assert current_stream() == self.compute_stream
self._signal_compute_done()
self._cpu_yield()
assert self.current_stream == self.compute_stream
self.update_stream(self.comm_stream)
self._wait_compute_done()
def yield_and_switch_from_comm_to_compute(self):
assert current_stream() == self.comm_stream
self._signal_comm_done()
self._cpu_yield()
assert self.current_stream == self.comm_stream
self.update_stream(self.compute_stream)
self._wait_comm_done()
def dbo_enabled() -> bool:
return len(_THREAD_ID_TO_CONTEXT) > 0
def dbo_current_ubatch_id() -> int:
if len(_THREAD_ID_TO_CONTEXT) == 0:
return 0
return _THREAD_ID_TO_CONTEXT[threading.get_ident()]
def _register_ubatch_function(func):
def wrapper(*args, **kwargs):
if len(_THREAD_ID_TO_CONTEXT) > 0:
ctx_idx = _THREAD_ID_TO_CONTEXT[threading.get_ident()]
ctx = _CURRENT_CONTEXTS[ctx_idx]
func(ctx, *args, **kwargs)
return wrapper
dbo_maybe_run_recv_hook = _register_ubatch_function(UBatchContext.maybe_run_recv_hook)
dbo_yield = _register_ubatch_function(UBatchContext.yield_)
dbo_yield_and_switch_from_compute_to_comm = _register_ubatch_function(
UBatchContext.yield_and_switch_from_compute_to_comm
)
dbo_yield_and_switch_from_comm_to_compute = _register_ubatch_function(
UBatchContext.yield_and_switch_from_comm_to_compute
)
dbo_switch_to_comm = _register_ubatch_function(UBatchContext.switch_to_comm)
dbo_switch_to_compute = _register_ubatch_function(UBatchContext.switch_to_compute)
dbo_switch_to_comm_sync = _register_ubatch_function(UBatchContext.switch_to_comm_sync)
dbo_switch_to_compute_sync = _register_ubatch_function(
UBatchContext.switch_to_compute_sync
)
def dbo_register_recv_hook(recv_hook):
if len(_THREAD_ID_TO_CONTEXT) > 0:
ctx_idx = _THREAD_ID_TO_CONTEXT[threading.get_ident()]
next_ctx = _CURRENT_CONTEXTS[(ctx_idx + 1) % 2]
next_ctx.recv_hook = recv_hook
def dbo_get_previous_event(func, *args, **kwargs):
if len(_THREAD_ID_TO_CONTEXT) > 0:
ctx_idx = _THREAD_ID_TO_CONTEXT[threading.get_ident()]
ctx = _CURRENT_CONTEXTS[ctx_idx]
# execute callable on the ubatch compute stream to record/wait events there
with torch.cuda.stream(ctx.compute_stream):
return func(*args, **kwargs)
def make_ubatch_contexts(
num_micro_batches: int,
compute_stream: torch.cuda.Stream,
comm_stream: torch.cuda.Stream,
forward_contexts: list[ForwardContext],
ready_barrier: threading.Barrier,
schedule: str = "default",
) -> list[UBatchContext]:
assert num_micro_batches == 2, "only been tested with 2 micro-batches"
"""
Create a context manager for micro-batching synchronization.
"""
cpu_events = [threading.Event() for _ in range(num_micro_batches)]
gpu_comm_done_events = [torch.cuda.Event() for _ in range(num_micro_batches)]
gpu_compute_done_events = [torch.cuda.Event() for _ in range(num_micro_batches)]
assert len(forward_contexts) == 2
ctxs = []
for i in range(num_micro_batches):
ctx = UBatchContext(
id=i,
compute_stream=compute_stream,
comm_stream=comm_stream,
forward_context=forward_contexts[i],
ready_barrier=ready_barrier,
cpu_wait_event=cpu_events[i],
cpu_signal_event=cpu_events[(i + 1) % num_micro_batches],
gpu_comm_done_event=gpu_comm_done_events[i],
gpu_compute_done_event=gpu_compute_done_events[i],
schedule=schedule,
)
ctxs.append(ctx)
return ctxs