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Commit 6e412916 authored by Tim Moon's avatar Tim Moon
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Add ZeRO-2 support in DistributedFusedAdam

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apex/contrib/optimizers/distributed_fused_adam_v2.py deleted 100644 → 0
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apex/contrib/optimizers/distributed_fused_adam_v3.py deleted 100644 → 0
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import math
import torch
import importlib
import amp_C
from apex.multi_tensor_apply import multi_tensor_applier
class DistributedFusedAdamV3(torch.optim.Optimizer):
"""Implements Adam algorithm. Currently GPU-only. Requires Apex to be installed via
``python setup.py install --cuda_ext --cpp_ext``.
It has been proposed in `Adam: A Method for Stochastic Optimization`_.
Arguments:
params (iterable): iterable of parameters to optimize or dicts defining
parameter groups.
lr (float, optional): learning rate. (default: 1e-3)
betas (Tuple[float, float], optional): coefficients used for computing
running averages of gradient and its square. (default: (0.9, 0.999))
eps (float, optional): term added to the denominator to improve
numerical stability. (default: 1e-8)
weight_decay (float, optional): weight decay (L2 penalty) (default: 0)
amsgrad (boolean, optional): whether to use the AMSGrad variant of this
algorithm from the paper `On the Convergence of Adam and Beyond`_
(default: False) NOT SUPPORTED in FusedAdam!
eps_inside_sqrt (boolean, optional): in the 'update parameters' step,
adds eps to the bias-corrected second moment estimate before
evaluating square root instead of adding it to the square root of
second moment estimate as in the original paper. (default: False)
use_mt (boolean, optional): use multi tensor apply for lower launch
latency. (default: False)
overlap_reductions(boolean, optional): whether to overlap reductions
with bprop (default: True)
num_prestats (integer, optional): number of fp64 stats that will be
reduced during first fp16 gradient reduction block.
.. _Adam\: A Method for Stochastic Optimization:
https://arxiv.org/abs/1412.6980
.. _On the Convergence of Adam and Beyond:
https://openreview.net/forum?id=ryQu7f-RZ
"""
def __init__(self, params,
lr=1e-3, bias_correction = True,
betas=(0.9, 0.999), eps=1e-8, eps_inside_sqrt = False,
weight_decay=0., max_grad_norm=0., amsgrad=False, use_mt=False,
amp_scale_adjustment=1.0, overlap_reductions=True, full_pipeline=True,
compute_L2_grad_norm=False, distributed_weight_update=0,
dwu_group_size=0, dwu_num_blocks=4, dwu_num_rs_pg=1, dwu_num_ar_pg=4,
dwu_num_ag_pg=0, revert_method=1, flat_mt=False,
dwu_num_chunks=4, predivide=True, e5m2_allgather=False,
do_not_flatten_model=False):
global fused_adam_cuda
fused_adam_cuda = importlib.import_module("fused_adam_cuda")
self._amp_scale_adjustment = amp_scale_adjustment
if use_mt:
raise RuntimeError('DistributedFusedAdam does not support use_mt.')
if amsgrad:
raise RuntimeError('DistributedFusedAdam does not support the AMSGrad variant.')
defaults = dict(lr=lr, bias_correction=bias_correction,
betas=betas, eps=eps, weight_decay=weight_decay,
max_grad_norm=max_grad_norm)
super(DistributedFusedAdamV3, self).__init__(params, defaults)
self.eps_mode = 0 if eps_inside_sqrt else 1
self._overflow_buf = torch.cuda.IntTensor([0])
assert (len(self.param_groups) == 1), "More than one parameter group is not supported."
# Way to revert a step
# 3 -> undo kernel + double buffer (debug, print norm of difference)
# 2 -> double buffer fp32 parameters
# 1 -> undo kernel
self._revert_method = revert_method
if self._revert_method > 1:
print("revert_method -> double buffer fp32 parameters, will consume more memory")
self._last_step = False
self._overlap_reductions = overlap_reductions
self._global_scale = None
self._num_blocks = dwu_num_blocks
self._predivide = predivide
self._e5m2_allgather = e5m2_allgather
self._do_not_flatten_model = do_not_flatten_model
self._full_pipeline = full_pipeline
self._L2_grad_norm = None
self._group_size = torch.cuda.device_count() if dwu_group_size <= 0 else dwu_group_size
self._world_size = torch.distributed.get_world_size()
self._num_groups = self._world_size // self._group_size
self._rank_in_group = torch.distributed.get_rank() % self._group_size
p_offset = 0
p_i = 0
self._param_state = None
self._model_params = []
self._grads_info = []
self._grad_accs = []
for group in self.param_groups:
self._param_group = group
prev = None
for p in group['params']:
torch.distributed.broadcast(p,0)
if not p.requires_grad:
continue
self._model_params.append(p)
state = self.state[p]
if len(state) == 0:
state['step'] = 0
if self._param_state is None:
self._param_state = state
p_grads_size = p.numel()
def wrapper(param, param_i, param_grads_size, param_offset):
param_tmp = param.expand_as(param)
grad_acc = param_tmp.grad_fn.next_functions[0][0]
def allreduce_hook(*unused):
self._do_overlapped_reduction(param_i, param_grads_size, param_offset, param)
grad_acc.register_hook(allreduce_hook)
self._grad_accs.append(grad_acc)
self._grads_info.append({"param_grads_size":p_grads_size, "param_offset":p_offset})
wrapper(p, p_i, p_grads_size, p_offset)
p_offset += p_grads_size
# Only enforce 128b alignment (64 * fp16) for non-consecutive parameters
# RNN is one example of consecutive parameters:
# (weight_ih, weight_hh, bias_ih, bias_hh)
if prev is not None and (prev.data_ptr() + prev.numel() * prev.element_size() != p.data_ptr()):
p_offset = ((p_offset + 63) // 64) * 64
prev = p
p_i += 1
self._grads_generated = [False]*len(self._grads_info)
self._flat_mt = flat_mt
self._grads = []
self._current_block = self._num_blocks
self._net_total_param_size = p_offset
self._total_param_size = p_offset
dwu_min_page_size = 256 * self._num_blocks * self._group_size
self._total_param_size = ((self._total_param_size + dwu_min_page_size - 1) // dwu_min_page_size) * dwu_min_page_size
self._block_size = self._total_param_size // self._num_blocks
self._shard_size = self._total_param_size // self._group_size
print("self._net_total_param_size=%d, self._total_param_size=%d, dwu_min_page_size=%d, self._block_size=%d, self._shard_size=%d" % (self._net_total_param_size, self._total_param_size,dwu_min_page_size,self._block_size,self._shard_size))
self._low_param_i = [0]*self._num_blocks
for block_id in range(self._num_blocks-1,-1,-1):
p_i = len(self._grads_info)-1
while p_i > 0 and self._grads_info[p_i]["param_offset"] > block_id*self._block_size:
p_i -= 1
self._low_param_i[block_id] = p_i
print(self._low_param_i)
self._flat_grads = torch.zeros([self._total_param_size], dtype=torch.float16, device='cuda')
self._flat_params = torch.zeros_like(self._flat_grads)
def _flat_split(flat):
def __flat_blockify(flat):
return [flat[block_id*self._block_size:(block_id+1)*self._block_size] for block_id in range(self._num_blocks)]
def __flat_shardify(flat):
return [flat[shard_id*self._shard_size:(shard_id+1)*self._shard_size] for shard_id in range(self._group_size)]
return __flat_blockify(flat), __flat_shardify(flat)
self._flat_grads_blocks, self._flat_grads_shards = _flat_split(self._flat_grads)
self._flat_params_blocks, self._flat_params_shards = _flat_split(self._flat_params)
# master params
self._fp32_p = torch.zeros([self._shard_size], dtype=torch.float32, device='cuda')
self._fp32_m = torch.zeros([self._shard_size], dtype=torch.float32, device='cuda')
self._fp32_v = torch.zeros([self._shard_size], dtype=torch.float32, device='cuda')
# copy model params to flat_params and set_ model params to flat_params.
self._individual_flat_grads = []
with torch.no_grad():
for p, grads_info in zip(self._model_params, self._grads_info):
start = grads_info["param_offset"]
end = start + grads_info["param_grads_size"]
flat_p = self._flat_params[start:end].view_as(p)
flat_p.copy_(p)
p.set_(flat_p)
flat_grad = self._flat_grads[start:end]
self._individual_flat_grads.append(flat_grad)
self._fp32_p.copy_(self._flat_params_shards[self._rank_in_group].float())
self._dwu_st = torch.cuda.Stream()
self._l2_grad_norm_st = torch.cuda.Stream()
for group_i in range(self._num_groups):
ranks = [group_i*self._group_size+local_rank for local_rank in range(self._group_size)]
pg = torch.distributed.new_group(ranks=ranks)
if torch.distributed.get_rank() in ranks:
self._ag_pg = pg
torch.distributed.all_reduce(self._overflow_buf, group=self._ag_pg)
import inspect
assert ('no_copy' in inspect.getfullargspec(torch.distributed.reduce_scatter).args), "This version of c10d does not support no_copy option"
@property
def has_overflow(self):
return True if not self.L2_grad_norm is None and not math.isfinite(self.L2_grad_norm) else False
def set_last_step(self, last_step):
self._last_step = last_step
def _get_flush_block(self):
flush_block = []
if self._current_block > 0 and self._grads_generated[self._low_param_i[self._current_block-1]]:
num_grads = len(self._grads_generated)
contiguous_idx = num_grads
while contiguous_idx > 0 and self._grads_generated[contiguous_idx-1]:
contiguous_idx -= 1
if contiguous_idx < num_grads and self._grads_info[contiguous_idx]["param_offset"] <= (self._current_block-1)*self._block_size:
self._current_block -= 1
start = self._current_block * self._block_size
end = (self._current_block+1) * self._block_size
flush_block = [start, end]
return flush_block
def __launch_step_kernel(self, p, p_copy, m, v, g):
combined_scale = self._global_scale
if self._param_group['max_grad_norm'] > 0 and math.isfinite(self.L2_grad_norm):
combined_scale = self._param_group['max_grad_norm'] / (self.L2_grad_norm / self._global_scale + 1e-6)
combined_scale = self._global_scale / min(1, combined_scale)
bias_correction = 1 if self._param_group['bias_correction'] else 0
beta1, beta2 = self._param_group['betas']
fused_adam_cuda.reversible_adam(
p, p_copy, m, v, g,
self._param_group['lr'],
beta1,
beta2,
self._param_group['eps'],
combined_scale,
self._param_state['step']+1,
self.eps_mode,
bias_correction,
self._param_group['weight_decay'])
def _flatten_grad_mt(self, scale):
if self._flat_mt and len(self._grads) > 0:
self._overflow_buf.zero_()
multi_tensor_applier(
amp_C.multi_tensor_scale,
self._overflow_buf,
list(zip(*self._grads)),
scale)
self._grads = []
def _do_overlapped_reduction(self, param_i, param_grads_size, param_offset, param):
# handle overlapped reductions
if self._flat_mt:
self._grads.append( (param.grad, self._individual_flat_grads[param_i]) )
else:
torch.div(param.grad, self._world_size if self._predivide else 1.0, out=self._individual_flat_grads[param_i])
self._grads_generated[param_i]=True
if not self._last_step and self._overlap_reductions:
flush_block = self._get_flush_block()
while flush_block:
block_id = flush_block[0] // self._block_size
self._dwu_st.wait_stream(torch.cuda.current_stream())
with torch.cuda.stream(self._dwu_st):
self._flatten_grad_mt(1.0/self._world_size if self._predivide else 1.0)
torch.distributed.all_reduce(self._flat_grads_blocks[block_id])
if block_id == 0:
self._l2_grad_norm_st.wait_stream(self._dwu_st)
with torch.cuda.stream(self._l2_grad_norm_st):
self._L2_grad_norm = self._flat_grads.norm(dtype=torch.float32, p=2).item()
flush_block = self._get_flush_block()
def set_global_scale(self, global_scale):
"""Set global scale.
"""
self._global_scale = global_scale
@property
def global_scale(self):
return self._global_scale
@property
def L2_grad_norm(self):
torch.cuda.current_stream().wait_stream(self._l2_grad_norm_st)
return self._L2_grad_norm
def complete_reductions(self):
"""Complete reductions if full pipeline is not selected or overlap is not allowed.
"""
if self._last_step:
# zero out gradients that have not been completed yet
for param_i, flat_grad in enumerate(self._individual_flat_grads):
if not self._grads_generated[param_i]:
flat_grad.zero_()
self._grads_generated[param_i] = True
if self._last_step or not self._overlap_reductions:
# nothing done so far, run full pipeline after reductions
self._dwu_st.wait_stream(torch.cuda.current_stream())
with torch.cuda.stream(self._dwu_st):
self._flatten_grad_mt(1.0/self._world_size if self._predivide else 1.0)
torch.distributed.all_reduce(self._flat_grads)
self._l2_grad_norm_st.wait_stream(self._dwu_st)
with torch.cuda.stream(self._l2_grad_norm_st):
self._L2_grad_norm = self._flat_grads.norm(dtype=torch.float32, p=2).item()
self._current_block = self._num_blocks
self._grads_generated = [False]*len(self._grads_info)
def step(self, closure=None, skip_overflow_check=False):
loss = None
if closure is not None:
loss = closure()
with torch.cuda.stream(self._dwu_st):
self.__launch_step_kernel(
self._fp32_p,
self._flat_params_shards[self._rank_in_group],
self._fp32_m,
self._fp32_v,
self._flat_grads_shards[self._rank_in_group])
torch.distributed.all_gather(self._flat_params_shards, self._flat_params_shards[self._rank_in_group], group=self._ag_pg, no_copy=True)
for p in self._model_params: self.state[p]['step'] += 1
torch.cuda.current_stream().wait_stream(self._dwu_st)
return loss
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