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Fix SAC BC breaking and renaming to ac_freq #397

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merged 3 commits into from
Jun 13, 2024
Merged

Fix SAC BC breaking and renaming to ac_freq #397

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195bcd6
Fix SAC BC breaking and renaming to ac_freq
wanchaol Jun 13, 2024
3e74f38
fix
wanchaol Jun 13, 2024
88e1754
fix
wanchaol Jun 13, 2024
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13 changes: 7 additions & 6 deletions torchtitan/parallelisms/parallelize_llama.py
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@
SequenceParallel,
)

from torch.utils.checkpoint import _pt2_selective_checkpoint_context_fn_gen, checkpoint
from torch.utils.checkpoint import checkpoint

from torchtitan.config_manager import JobConfig, TORCH_DTYPE_MAP
from torchtitan.logging_utils import logger
Expand All @@ -45,6 +45,7 @@
# currently selective per op and per layer checkpointing are supported
def checkpoint_wrapper(module, config):
if config.mode == "selective" and config.selective_ac_option == "op":
from torch.utils.checkpoint import create_selective_checkpoint_contexts
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Hey, sorry for bc-breaking! I've updated the top of the PR description to have a list of things to restore prior behavior -

Two updates below that are still needed for your case:

  • return a CheckpointPolicy Enum instead of bool
  • accept a ctx: SelectiveCheckpoint instead of mode: str
def _custom_policy(ctx, func, *args, **kwargs):
      mode = "recompute" if ctx.is_recompute else "forward"
      mm_count_key = f"{mode}_mm_count"
      if func == torch.ops.aten.mm.default:
          meta[mm_count_key] += 1
      # Saves output of all compute ops, except every second mm
      to_save =  func in no_recompute_list and not (
          func == torch.ops.aten.mm.default and meta[mm_count_key] % 2 == 0
      )
      return CheckpointPolicy.MUST_SAVE if to_save else CheckpointPolicy.PREFER_RECOMPUTE


def _get_custom_policy(meta):
def _custom_policy(mode, func, *args, **kwargs):
Expand All @@ -60,7 +61,7 @@ def _custom_policy(mode, func, *args, **kwargs):

def selective_checkpointing_context_fn():
meta = defaultdict(int)
return _pt2_selective_checkpoint_context_fn_gen(_get_custom_policy(meta))
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Hey @wanchaol, I think this PR (or #397) might have broken SAC + compile. I didn't verify though since _pt2_selective_checkpoint_context_fn_gen isn't in PyTorch trunk anymore. Do you think it's due to this change, or SAC + compile was already broken?

return create_selective_checkpoint_contexts(_get_custom_policy(meta))

return ptd_checkpoint_wrapper(
module,
Expand All @@ -86,15 +87,15 @@ def selective_checkpointing_context_fn():
1 == checkpointing every one (all).
2 == checkpoint every 2nd one
"""
every_x_layer = int(config.selective_ac_option)
ac_freq = int(config.selective_ac_option)
assert (
every_x_layer >= 0
), f"selective layer AC policy (every_x_layer) expects a positive integer, received {every_x_layer}"
ac_freq >= 0
), f"selective layer AC policy (ac_freq) expects a positive integer, received {ac_freq}"

checkpoint_wrapper.__dict__.setdefault("_count", 0)

checkpoint_wrapper._count += 1
if not every_x_layer or checkpoint_wrapper._count % every_x_layer == 0:
if not ac_freq or checkpoint_wrapper._count % ac_freq == 0:
return ptd_checkpoint_wrapper(
module,
checkpoint_impl=CheckpointImpl.NO_REENTRANT,
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