ColossalAI/colossalai/legacy/nn/parallel/reducer.py
Hongxin Liu 554aa9592e
[legacy] move communication and nn to legacy and refactor logger (#4671)
* [legacy] move communication to legacy (#4640)

* [legacy] refactor logger and clean up legacy codes (#4654)

* [legacy] make logger independent to gpc

* [legacy] make optim independent to registry

* [legacy] move test engine to legacy

* [legacy] move nn to legacy (#4656)

* [legacy] move nn to legacy

* [checkpointio] fix save hf config

* [test] remove useledd rpc pp test

* [legacy] fix nn init

* [example] skip tutorial hybriad parallel example

* [devops] test doc check

* [devops] test doc check
2023-09-11 16:24:28 +08:00

117 lines
3.8 KiB
Python

# Copyright (c) Facebook, Inc. and its affiliates.
#
# This source code is licensed under the BSD license found in the
# LICENSE file in the root directory of this source tree.
import functools
from typing import Callable, Dict, List, Optional, Tuple
import torch
import torch.distributed as dist
from torch import Tensor
from torch.distributed import ProcessGroup
class Bucket:
def __init__(self, size: int, dtype: torch.dtype, device: torch.device, group: ProcessGroup):
self.buffer = torch.zeros(size, dtype=dtype, device=device)
self.group = group
self.offset = 0
self.callbacks: List[Callable] = []
def flush(self) -> None:
"""Flush content of the bucket."""
if self.offset == 0:
assert len(self.callbacks) == 0
return
# reduce-scatter bucket
dist.all_reduce(self.buffer[:self.offset], group=self.group)
# execute post-reduction callbacks
for callback_fn in self.callbacks:
callback_fn()
# reuse input bucket but allocate a fresh output shard
self.offset = 0
self.callbacks.clear()
self.buffer = torch.zeros_like(self.buffer)
def alloc(self) -> None:
if self.buffer.storage().size() == 0:
self.buffer.storage().resize_(self.buffer.numel())
def free(self) -> None:
assert self.offset == 0 and self.callbacks == [], "Incorrect call of teardown"
self.buffer.storage().resize_(0)
def append(self, tensor: Tensor, callback_fn: Callable):
tensor_size = tensor.numel()
offset = self.offset
self.buffer[offset:offset + tensor_size].copy_(tensor.flatten())
self.offset += tensor_size
# callback will be given the reduced result
if callback_fn is not None:
result_view = self.buffer[offset:offset + tensor_size].view(tensor.shape)
self.callbacks.append(functools.partial(callback_fn, result_view))
@property
def avail_size(self) -> int:
return self.buffer.size(0) - self.offset
class Reducer:
def __init__(self, bucket_size_mb: int = 25):
self.bucket_size_mb = bucket_size_mb
self.buckets: Dict[Tuple[torch.dtype, torch.device, ProcessGroup], Bucket] = {}
@torch.no_grad()
def all_reduce_async(
self,
tensor: Tensor,
group: ProcessGroup,
callback_fn: Optional[Callable] = None,
) -> None:
bucket_size = self._get_bucket_size(tensor.element_size())
if tensor.numel() >= bucket_size:
dist.all_reduce(tensor, group=group)
if callback_fn is not None:
callback_fn(tensor)
return
bucket = self._get_bucket(tensor, group)
if tensor.numel() > bucket.avail_size:
# not enough space remaining in bucket, flush it now
bucket.flush()
bucket.append(tensor, callback_fn)
@torch.no_grad()
def flush(self) -> None:
for bucket in self.buckets.values():
bucket.flush()
@torch.no_grad()
def free(self) -> None:
for bucket in self.buckets.values():
bucket.free()
@functools.lru_cache()
def _get_bucket_size(self, element_size: int) -> int:
if self.bucket_size_mb <= 0: # Values <= 0 disable bucketing.
return 0
MB = 1024 * 1024
bucket_size = self.bucket_size_mb * MB / element_size
return int(bucket_size)
def _get_bucket(self, tensor: Tensor, group: ProcessGroup) -> Bucket:
key = (tensor.dtype, tensor.device, group)
if key not in self.buckets:
bucket_size = self._get_bucket_size(tensor.element_size())
self.buckets[key] = Bucket(bucket_size, tensor.dtype, tensor.device, group)
self.buckets[key].alloc()
return self.buckets[key]