Files
2026-07-13 13:18:33 +08:00

288 lines
11 KiB
Python

# Copyright (c) Microsoft Corporation.
# SPDX-License-Identifier: Apache-2.0
# DeepSpeed Team
import torch
from deepspeed import comm as dist
def print_rank_0(message):
if dist.get_rank() == 0:
print(message)
class ContiguousMemoryAllocator(object):
def __init__(self, size, dtype, device):
self.buffer = torch.zeros(size, dtype=dtype, device=device)
#address to contiguous size available
self.contiguous_sizes = {}
self.contiguous_sizes[0] = size
#tensor id to its address
self.tensor_addresses = {}
#tensor address to its size
self.tensor_sizes = {}
#tensor address to ids
self.tensor_ids = {}
#id to tensors
self.tensor_map = {}
#id to params. Maps each tensor buffer to list of parameters that uses it
self.id_to_params = {}
self.total_size = size
self.total_free = size
self.largest_contiguous = size
self.max_allocated = 0
self.count = 0
#create a tensor of size from the pre-allocated buffer
#if not enough free space will fail
#if not enough contiguous space, will defragment and allocate
def allocate_tensor(self, size):
free_before = self.total_free
assert size <= self.total_free, "Not enough memory in buffer. Allocation failed"
if self.largest_contiguous < size:
print_rank_0("Needs defragmentation to allocate. Before Defragmentation:")
self.print_allocation(resolution=100)
self._defragment_memory()
#set the param data to the new tensor buffer locations
self._reset_param_data()
print_rank_0("After defragmentation:")
self.print_allocation(resolution=100)
self.total_free = self.total_free - size
allocated = self.total_size - self.total_free
if allocated > self.max_allocated:
self.max_allocated = allocated
tensor_address = self._get_new_tensor_address(size)
ret_tensor = self._get_new_tensor(tensor_address, size)
print_rank_0(
f"Free before allocation {free_before}. Allocating {size}. Free after allocation {self.total_free}. Max allocated {self.max_allocated}"
)
assert self.total_free + size == free_before, "Allocation bookkeeping error"
return ret_tensor
#assigns the tensor data to the param data and keeps track of the assignment
#any change the underlying buffer from defragmentation will cause a
#reassignment of the param data
def assign_to_param(self, tensor, param, numel, shape):
tensor_id = id(tensor)
assert tensor_id in self.tensor_map.keys(), "No such tensor allocated by the allocator."
assert tensor.numel() >= numel, "Assert tensor buffer does is not large enough"
assert tensor_id not in self.id_to_params.keys(), "This tensor has already been assigned to a param"
self.id_to_params[tensor_id] = [param]
replicated_tensor = tensor.narrow(0, 0, numel).view(shape)
param.data = replicated_tensor.data
param.contiguous_tensor_id = tensor_id
#deletes the tensor and frees up the underlying buffer
def release_tensor(self, tensor):
free_before = self.total_free
tensor_id = id(tensor)
tensor_size = tensor.numel()
self._release_tensor(tensor_id)
self._unassign_params(tensor_id)
self.total_free += tensor_size
print_rank_0(
f"Free before release {free_before}. Released {tensor.numel()}. Total free after {self.total_free}.")
assert self.total_free - tensor_size == free_before, "Release bookkeeping error"
def release_tensor_with_id(self, tensor_id):
free_before = self.total_free
assert tensor_id in self.tensor_map.keys(), "Invalid tensor id"
tensor = self.tensor_map[tensor_id]
tensor_size = tensor.numel()
self._release_tensor(tensor_id)
self._unassign_params(tensor_id)
self.total_free += tensor_size
print_rank_0(
f"Free before release {free_before}. Released {tensor.numel()}. Total free after {self.total_free}.")
assert self.total_free - tensor_size == free_before, "Release bookkeeping error"
#shows the current memory allocation at specified resolution
def print_allocation(self, resolution=200):
total_size = self.buffer.numel() * 1.0
empty = []
for addr, size in self.contiguous_sizes.items():
start = int(addr * resolution / total_size)
end = int((addr + size) * resolution / total_size)
empty.extend(range(start, end))
s = ''
for i in range(resolution):
s += '.' if i in empty else '|'
print_rank_0(s)
def max_allocated(self):
return self.max_allocated
#to be called after defragmentation that moves the tensor buffers
#this call reassigns the data of all the parameters using the tensor buffers
def _reset_param_data(self):
for id, tensor in self.tensor_map.items():
for param in self.id_to_params[id]:
param.data = tensor.narrow(0, 0, param.numel()).view(param.data.shape).data
def _unassign_params(self, tensor_id):
if tensor_id in self.id_to_params.keys():
del self.id_to_params[tensor_id]
def _release_tensor(self, tensor_id):
assert tensor_id in self.tensor_addresses, f"Tensor id {tensor_id} not found"
address = self.tensor_addresses[tensor_id]
contiguous_size = self.tensor_map[tensor_id].numel()
del self.tensor_addresses[tensor_id]
del self.tensor_ids[address]
del self.tensor_map[tensor_id]
del self.tensor_sizes[address]
self._consolidate_address(address, contiguous_size)
self.largest_contiguous = self._largest_contiguous()
def _consolidate_address(self, address, contiguous_size):
#consolidate next buffer
end_address = address + contiguous_size
if end_address in self.contiguous_sizes:
contiguous_size += self.contiguous_sizes[end_address]
del self.contiguous_sizes[end_address]
#consolidate previous buffer
for addr, size in self.contiguous_sizes.items():
if addr + size == address:
del self.contiguous_sizes[addr]
contiguous_size += size
address = addr
break
self.contiguous_sizes[address] = contiguous_size
def _defragment_memory(self):
empty_addresses = sorted(self.contiguous_sizes.keys())
tensor_addresses = sorted(self.tensor_addresses.values())
tensor_index = 0
while tensor_index < len(tensor_addresses):
empty_addr = empty_addresses[0]
empty_size = self.contiguous_sizes[empty_addr]
tensor_addr = tensor_addresses[tensor_index]
tensor_size = self.tensor_sizes[tensor_addr]
tensor_id = self.tensor_ids[tensor_addr]
tensor = self.tensor_map[self.tensor_ids[tensor_addr]]
assert tensor_size == tensor.numel(), \
f"Size mismatch. {tensor_size} is allocated at addr {tensor_addr} but tensor size is {tensor.numel()} "
assert empty_addr != tensor_addr, \
f"Cannot have same empty address {empty_addr} and tensor address {tensor_addr}"
if empty_addr < tensor_addr:
if empty_size >= tensor_size:
dest_buffer = self.buffer.narrow(0, empty_addr, tensor_size)
src_buffer = self.buffer.narrow(0, tensor_addr, tensor_size)
dest_buffer.data.copy_(src_buffer.data)
else:
#print_rank_0(f'empty addr : {empty_addr}, empty size {empty_size} tensor addr {tensor_addr} tensor size {tensor_size}')
src_addr = tensor_addr
dest_addr = empty_addr
while src_addr < (tensor_addr + tensor_size):
copy_size = min(empty_size, tensor_addr + tensor_size - src_addr)
dest_buffer = self.buffer.narrow(0, dest_addr, copy_size)
src_buffer = self.buffer.narrow(0, src_addr, copy_size)
dest_buffer.data.copy_(src_buffer.data)
src_addr += copy_size
dest_addr += copy_size
self._replace_old_address_with_new(tensor_id, empty_addr)
tensor_index += 1
else:
tensor_index += 1
empty_addresses = sorted(self.contiguous_sizes.keys())
def _replace_old_address_with_new(self, tensor_id, new_address):
tensor = self.tensor_map[tensor_id]
tensor_size = tensor.numel()
tensor.data = self.buffer.narrow(0, new_address, tensor_size).data
self._release_tensor(tensor_id)
self._mark_as_occupied(new_address, tensor_size)
self.tensor_ids[new_address] = tensor_id
self.tensor_map[tensor_id] = tensor
self.tensor_addresses[tensor_id] = new_address
self.tensor_sizes[new_address] = tensor_size
def _get_new_tensor_address(self, size):
tensor_address = None
for address, contiguous_size in self.contiguous_sizes.items():
if contiguous_size >= size and \
(tensor_address is None or \
contiguous_size < self.contiguous_sizes[tensor_address]):
tensor_address = address
assert tensor_address is not None, "address cannot be None"
return tensor_address
def _get_new_tensor(self, address, size):
available_contiguous_size = self.contiguous_sizes[address]
assert size <= available_contiguous_size, \
f"Tensor numel {size} is large than available contiguous size {available_contiguous_size}"
self.count += 1
new_tensor = self.buffer.narrow(0, address, size)
tensor_id = id(new_tensor)
self.tensor_addresses[tensor_id] = address
self.tensor_sizes[address] = size
self.tensor_ids[address] = tensor_id
self.tensor_map[tensor_id] = new_tensor
self._mark_as_occupied(address, size)
return new_tensor
def _largest_contiguous(self):
if len(self.contiguous_sizes) > 0:
return max([size for _, size in self.contiguous_sizes.items()])
else:
return 0
def _mark_as_occupied(self, address, size):
available_contiguous_size = self.contiguous_sizes[address]
del self.contiguous_sizes[address]
if available_contiguous_size != size:
self.contiguous_sizes[address + size] = available_contiguous_size - size
self.largest_contiguous = self._largest_contiguous()