blt/bytelatent/norms.py
Pedro Rodriguez bc39591032 Several changes to enable entropy model training/eval
Summary:

- Make arrow iterator able to read from jsonl files, the entropies are omitted in this case
- Make the data/checkpoint code fsspec compatible
- Fix issues with all reduce with non-bf16 in dist_sum and norm computation.
- Minimal fixes to get eval to run, it is slow currently
- Add bpb numbers during training


Test Plan:

Run

```
torchrun --nproc-per-node 8 -m bytelatent.train config=internal/configs/entropy_model.yaml eval=null max_steps=10100
```

```
python -m bytelatent.train config=internal/configs/s3_debug.yaml eval=null
```

```
torchrun --nproc-per-node 8 -m bytelatent.train config=internal/configs/s3_debug.yaml eval=null
```
2025-02-04 18:19:49 +00:00

101 lines
4.2 KiB
Python

from typing import Dict, List, Optional, Tuple
import torch
from torch import Tensor
from torch.utils._foreach_utils import (
_device_has_foreach_support,
_group_tensors_by_device_and_dtype,
_has_foreach_support,
)
@torch.no_grad()
def fixed_clip_grad_norm_(
parameters: torch.Tensor | list[torch.Tensor],
max_norm: float,
norm_type: float = 2.0,
error_if_nonfinite: bool = False,
foreach: Optional[bool] = None,
) -> torch.Tensor:
r"""Clip the gradient norm of an iterable of parameters.
The norm is computed over the norms of the individual gradients of all parameters,
as if the norms of the individual gradients were concatenated into a single vector.
Gradients are modified in-place.
Args:
parameters (Iterable[Tensor] or Tensor): an iterable of Tensors or a
single Tensor that will have gradients normalized
max_norm (float): max norm of the gradients
norm_type (float): type of the used p-norm. Can be ``'inf'`` for
infinity norm.
error_if_nonfinite (bool): if True, an error is thrown if the total
norm of the gradients from :attr:`parameters` is ``nan``,
``inf``, or ``-inf``. Default: False (will switch to True in the future)
foreach (bool): use the faster foreach-based implementation.
If ``None``, use the foreach implementation for CUDA and CPU native tensors and silently
fall back to the slow implementation for other device types.
Default: ``None``
Returns:
Total norm of the parameter gradients (viewed as a single vector).
"""
if isinstance(parameters, torch.Tensor):
parameters = [parameters]
grads = [p.grad.to(torch.bfloat16) for p in parameters if p.grad is not None]
max_norm = float(max_norm)
norm_type = float(norm_type)
if len(grads) == 0:
return torch.tensor(0.0)
first_device = grads[0].device
grouped_grads: Dict[
Tuple[torch.device, torch.dtype], Tuple[List[List[Tensor]], List[int]]
] = _group_tensors_by_device_and_dtype(
[grads]
) # type: ignore[assignment]
norms: List[Tensor] = []
for (device, _), ([device_grads], _) in grouped_grads.items(): # type: ignore[assignment]
if (foreach is None and _has_foreach_support(device_grads, device)) or (
foreach and _device_has_foreach_support(device)
):
norms.extend(torch._foreach_norm(device_grads, norm_type))
elif foreach:
raise RuntimeError(
f"foreach=True was passed, but can't use the foreach API on {device.type} tensors"
)
else:
norms.extend([torch.linalg.vector_norm(g, norm_type) for g in device_grads])
total_norm = torch.linalg.vector_norm(
torch.stack([norm.to(first_device) for norm in norms]), 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`"
)
clip_coef = max_norm / (total_norm + 1e-6)
# Note: multiplying by the clamped coef is redundant when the coef is clamped to 1, but doing so
# avoids a `if clip_coef < 1:` conditional which can require a CPU <=> device synchronization
# when the gradients do not reside in CPU memory.
clip_coef_clamped = torch.clamp(clip_coef, max=1.0)
for (device, _), ([device_grads], _) in grouped_grads.items(): # type: ignore[assignment]
if (foreach is None and _has_foreach_support(device_grads, device)) or (
foreach and _device_has_foreach_support(device)
):
torch._foreach_mul_(device_grads, clip_coef_clamped.to(device))
elif foreach:
raise RuntimeError(
f"foreach=True was passed, but can't use the foreach API on {device.type} tensors"
)
else:
clip_coef_clamped_device = clip_coef_clamped.to(device)
for g in device_grads:
g.mul_(clip_coef_clamped_device)
return total_norm