Deprecate Fused LayerNorm (#2475)

Will be removed in v0.18.
mosaicml · Aug 28, 2023 · 23aaaeb · 23aaaeb
1 parent a6c0b0f
commit 23aaaeb
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diff --git a/composer/algorithms/fused_layernorm/fused_layernorm.py b/composer/algorithms/fused_layernorm/fused_layernorm.py
@@ -46,6 +46,10 @@ def apply_fused_layernorm(model: torch.nn.Module, optimizers: Union[torch.optim.
 
     By fusing multiple kernel launches into one, this usually improves GPU utilization.
     """
+    warnings.warn(
+        DeprecationWarning(
+            'Fused LayerNorm has been deprecated and will be removed in Composer 0.18. Please switch to Low Precision LayerNorm.'
+        ))
     check_if_apex_installed()
 
     # prepare the replacement policy and perform replacement
@@ -99,6 +103,10 @@ def no_op(self, *args): pass
 
     def __init__(self):
         # FusedLayerNorm takes no arguments
+        warnings.warn(
+            DeprecationWarning(
+                'Fused LayerNorm has been deprecated and will be removed in Composer 0.18. Please switch to Low Precision LayerNorm.'
+            ))
         check_if_apex_installed()
 
     def __repr__(self) -> str:

diff --git a/composer/algorithms/low_precision_layernorm/low_precision_layernorm.py b/composer/algorithms/low_precision_layernorm/low_precision_layernorm.py
@@ -6,6 +6,7 @@
 from __future__ import annotations
 
 import logging
+import textwrap
 import warnings
 from typing import Dict, Optional, Sequence, Type, Union
 
@@ -40,6 +41,14 @@ def apply_low_precision_layernorm(model,
     # Prior to v1.13, torch.nn.LayerNorm is slow in bf16 precision.
     # We use FusedLayerNorm as a fallback.
     if version.parse(torch.__version__) < version.parse('1.13') and precision == Precision.AMP_BF16:
+        warnings.warn(
+            DeprecationWarning(
+                textwrap.dedent(
+                    'You are using Low Precision LayerNorm on PyTorch < v.1.13 with bfloat16 precision. '
+                    'In this scenario, we fall back to Fused LayerNorm. '
+                    'Fused LayerNorm has been deprecated and will be removed in Composer 0.18. '
+                    'Please upgrade your PyTorch version to >=v.1.13 to use Low Precision LayerNorm without the Fused LayerNorm fallback.'
+                )))
         check_if_apex_installed()
         policy: Dict[Type[torch.nn.Module], module_surgery.ReplacementFunction] = {
             torch.nn.LayerNorm: _to_FusedLayerNorm