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[Dev] remove dead manual_release_grads code path in 1F1B overlap schedule #4510

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Merged
ko3n1g merged 1 commit into from
Apr 29, 2026
Merged

[Dev] remove dead manual_release_grads code path in 1F1B overlap schedule #4510

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13 changes: 0 additions & 13 deletions megatron/core/models/gpt/fine_grained_callables.py
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Original file line number Diff line number Diff line change
Expand Up @@ -316,12 +316,6 @@ def backward_impl(self, outputs, output_grad):
detached_grad = tuple([e.grad for e in self.detached])
grads = output_grad + detached_grad
self.default_backward_func(outputs + self.before_detached, grads)
# release the output grad memory after backward finishes,
# except when delay_wgrad_comptue is enabled, the grad should be
# kept until all modules' backward_dw has been invoked.
if self.delay_wgrad_compute:
self.output_grads = grads
self.delay_grads_release = len(self.bwd_dw_callables) > 0

# return grads for record stream
return grads
Expand All @@ -339,13 +333,6 @@ def backward_dw(self):
module.backward_dw()
nvtx_range_pop(nvtx_msg)

# the output grad memory is last used in wgrad compute, should be safe to release.
assert self.delay_grads_release, "output grad memory should be valid before wgrad."
if self.manual_release_grads:
for tensor in self.output_grads:
tensor.untyped_storage().resize_(0)
self.output_grads = None

self.bwd_dw_callables = None

def __del__(self):
Expand Down
8 changes: 0 additions & 8 deletions megatron/core/pipeline_parallel/utils.py
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Original file line number Diff line number Diff line change
Expand Up @@ -182,8 +182,6 @@ def __init__(
self.free_input = free_input
self.inputs = None
self.outputs = None
self.delay_grads_release = False
self.manual_release_grads = False

def default_backward_func(self, outputs, output_grad):
"""Default backward function"""
Expand Down Expand Up @@ -263,12 +261,6 @@ def _backward(self, *output_grad):
for g in output_grad:
if g is not None:
g.record_stream(self.stream)
# Manually trigger the memory release of dgrad tensor
# to avoid delayed garbage collection. If
# delay_grads_release is True, dgrad is last used in
# wgrad compute and skip the release here.
if self.manual_release_grads and not self.delay_grads_release:
g.untyped_storage().resize_(0)

grads = self.get_grad()
self._release_state()
Expand Down
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