def calc_params_l2_norm(model):
"""Calculate l2 norm of parameters """
args = get_args()
if not isinstance(model, list):
model = [model]
# Remove duplicate params.
params_data = []
for model_ in model:
for param in model_.parameters():
is_not_shared = param_is_not_shared(param)
is_not_tp_duplicate = param_is_not_tensor_parallel_duplicate(param)
if is_not_shared and is_not_tp_duplicate:
if args.bf16:
params_data.append(param.data.float())
else:
params_data.append(param.data)
# Calculate norm
dummy_overflow_buf = torch.cuda.IntTensor([0])
norm, _ = multi_tensor_applier(
amp_C.multi_tensor_l2norm,
dummy_overflow_buf,
[params_data],
False # no per-parameter norm
)
norm_2 = norm * norm
# Sum across all model-parallel GPUs.
torch.distributed.all_reduce(norm_2,
op=torch.distributed.ReduceOp.SUM,
group=mpu.get_model_parallel_group())
return norm_2.item() ** 0.5
def count_zeros_fp32(parameters):
if isinstance(parameters, torch.Tensor):
parameters = [parameters]
# Filter parameters based on:
# - grad should not be none
# - parameter should not be shared
# - should not be a replica due to tensor model parallelism
total_num_zeros = 0.0
for param in parameters:
grad_not_none = param.grad is not None
is_not_shared = param_is_not_shared(param)
is_not_tp_duplicate = param_is_not_tensor_parallel_duplicate(param)
if grad_not_none and is_not_shared and is_not_tp_duplicate:
grad = param.grad.detach()
num_zeros = grad.numel() - torch.count_nonzero(grad)
total_num_zeros = num_zeros + total_num_zeros
# Sum across all model-parallel GPUs.
torch.distributed.all_reduce(total_num_zeros,
op=torch.distributed.ReduceOp.SUM,
group=mpu.get_model_parallel_group())
total_num_zeros = total_num_zeros.item()
return total_num_zeros
def clip_grad_norm_fp32(parameters, max_norm, norm_type=2):
"""Clips gradient norm of an iterable of parameters whose gradients
are in fp32.
This is adapted from torch.nn.utils.clip_grad.clip_grad_norm_ and
added functionality to handle model parallel parameters. Note that
the gradients are modified in place.
Arguments:
parameters (Iterable[Tensor] or Tensor): an iterable of Tensors or a
single Tensor that will have gradients normalized
max_norm (float or int): max norm of the gradients
norm_type (float or int): type of the used p-norm. Can be ``'inf'`` for
infinity norm.
Returns:
Total norm of the parameters (viewed as a single vector).
"""
if isinstance(parameters, torch.Tensor):
parameters = [parameters]
# Filter parameters based on:
# - grad should not be none
# - parameter should not be shared
# - should not be a replica due to tensor model parallelism
grads = []
grads_for_norm = []
for param in parameters:
grad_not_none = param.grad is not None
is_not_shared = param_is_not_shared(param)
is_not_tp_duplicate = param_is_not_tensor_parallel_duplicate(param)
if grad_not_none:
grad = param.grad.detach()
if grad_not_none:
# Make sure the grads are in fp32
assert param.grad.type() == 'torch.cuda.FloatTensor'
grads.append(grad)
if grad_not_none and is_not_shared and is_not_tp_duplicate:
grads_for_norm.append(grad)
# Norm parameters.
max_norm = float(max_norm)
norm_type = float(norm_type)
total_norm = 0.0
# Calculate norm.
if norm_type == inf:
total_norm = max(grad.abs().max() for grad in grads_for_norm)
total_norm_cuda = torch.cuda.FloatTensor([float(total_norm)])
# Take max across all model-parallel GPUs.
torch.distributed.all_reduce(total_norm_cuda,
op=torch.distributed.ReduceOp.MAX,
group=mpu.get_model_parallel_group())
total_norm = total_norm_cuda[0].item()
else:
if norm_type == 2.0:
dummy_overflow_buf = torch.cuda.IntTensor([0])
# Use apex's multi-tensor applier for efficiency reasons.
# Multi-tensor applier takes a function and a list of list
# and performs the operation on that list all in one kernel.
grad_norm, _ = multi_tensor_applier(
amp_C.multi_tensor_l2norm,
dummy_overflow_buf,
[grads_for_norm],
False # no per-parameter norm
)
# Since we will be summing across data parallel groups,
# we need the pow(norm-type).
total_norm = grad_norm ** norm_type
else:
for grad in grads_for_norm:
grad_norm = torch.norm(grad, norm_type)
total_norm += grad_norm ** norm_type
# Sum across all model-parallel GPUs.
torch.distributed.all_reduce(total_norm,
op=torch.distributed.ReduceOp.SUM,
group=mpu.get_model_parallel_group())
total_norm = total_norm.item() ** (1.0 / norm_type)
# Scale.
clip_coeff = max_norm / (total_norm + 1.0e-6)
if clip_coeff < 1.0:
dummy_overflow_buf = torch.cuda.IntTensor([0])
multi_tensor_applier(amp_C.multi_tensor_scale,
dummy_overflow_buf,
[grads, grads],
clip_coeff)
return total_norm