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Original file line number | Diff line number | Diff line change |
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import torch | ||
|
||
# for backwards compatibility with pytorch 1.13 | ||
try: | ||
from torch._six import inf | ||
except ImportError: | ||
from torch import inf | ||
|
||
import torch.distributed as dist | ||
from collections import defaultdict | ||
|
||
|
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def get_total_norm(tensors, norm_type, error_if_nonfinite): | ||
if len(tensors) == 0: | ||
return torch.tensor(0.0) | ||
device = tensors[0].device | ||
total_norm = torch.norm( | ||
torch.stack([torch.norm(g.detach(), norm_type).to(device) for g in tensors]), | ||
norm_type, | ||
) | ||
if error_if_nonfinite and torch.logical_or(total_norm.isnan(), total_norm.isinf()): | ||
raise RuntimeError( | ||
f"The total norm of order {norm_type} for gradients from " | ||
"`parameters` is non-finite, so it cannot be clipped. To disable " | ||
"this error and scale the gradients by the non-finite norm anyway, " | ||
"set `error_if_nonfinite=False`" | ||
) | ||
|
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return total_norm | ||
|
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def clip_grad_norm_(parameters, max_norm, norm_type=2.0, error_if_nonfinite=False): | ||
if norm_type == inf: | ||
raise NotImplementedError | ||
|
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if isinstance(parameters, torch.Tensor): | ||
parameters = [parameters] | ||
|
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tensor_parallel_params = defaultdict(list) | ||
non_tensor_parallel_params = [] | ||
for p in parameters: | ||
if hasattr(p, "is_tensor_parallel") and p.is_tensor_parallel: | ||
assert hasattr( | ||
p, "process_group_for_norm_reduction" | ||
), "each tensor parallel tensor should" | ||
"have a process group for all-reducing norms" | ||
tensor_parallel_params[p.process_group_for_norm_reduction].append(p) | ||
else: | ||
non_tensor_parallel_params.append(p) | ||
|
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tensor_parallel_grads = {} | ||
for process_group, group_params in tensor_parallel_params.items(): | ||
tensor_parallel_grads[process_group] = [ | ||
p.grad for p in group_params if p.grad is not None | ||
] | ||
|
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non_tensor_parallel_grads = [ | ||
p.grad for p in non_tensor_parallel_params if p.grad is not None | ||
] | ||
|
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max_norm = float(max_norm) | ||
norm_type = float(norm_type) | ||
|
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non_tensor_parallel_norm = get_total_norm( | ||
non_tensor_parallel_grads, norm_type, error_if_nonfinite | ||
) | ||
|
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tensor_parallel_norms = [] | ||
for process_group, grads in tensor_parallel_grads.items(): | ||
local_tensor_parallel_norm = get_total_norm( | ||
grads, norm_type, error_if_nonfinite | ||
) | ||
tensor_parallel_norm = local_tensor_parallel_norm**norm_type | ||
dist.all_reduce(tensor_parallel_norm, group=process_group) | ||
tensor_parallel_norm = tensor_parallel_norm ** (1.0 / norm_type) | ||
tensor_parallel_norms.append(tensor_parallel_norm) | ||
|
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all_norms = tensor_parallel_norms + [non_tensor_parallel_norm] | ||
total_norm = get_total_norm(all_norms, norm_type, error_if_nonfinite) | ||
|
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clip_coef = max_norm / (total_norm + 1e-6) | ||
clip_coef_clamped = torch.clamp(clip_coef, max=1.0) | ||
for g in non_tensor_parallel_grads: | ||
g.detach().mul_(clip_coef_clamped.to(g.device)) | ||
|
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for group_grads in tensor_parallel_grads.values(): | ||
for g in group_grads: | ||
g.detach().mul_(clip_coef_clamped.to(g.device)) | ||
|
||
return total_norm |
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