Make promote_high_prefetch_overheaad_table_to_hbm a static function so other proposer can reuse (#2191)

Summary:
Pull Request resolved: #2191

As titled. This function is proven to be useful across all embedding offloading related planning. Make it a static function so other proposer can use it.

Reviewed By: henrylhtsang

Differential Revision: D59136171

fbshipit-source-id: 0f0fec8895711e1c84990bc1181e571e4185bee1

Author: levythu

torchrec/distributed/planner/proposers.py

@@ -309,11 +309,14 @@ def load(
         ]
         # deepcopy so it won't affect other proposers
         self.starting_proposal = copy.deepcopy(proposal)
-        self.promote_high_prefetch_overheaad_table_to_hbm(self.starting_proposal)
+        self.promote_high_prefetch_overheaad_table_to_hbm(
+            self.enumerator, self.starting_proposal
+        )
         self.proposal = copy.deepcopy(self.starting_proposal)
 
+    @staticmethod
     def promote_high_prefetch_overheaad_table_to_hbm(
-        self, proposal: List[ShardingOption]
+        enumerator: Optional[Enumerator], proposal: List[ShardingOption]
     ) -> None:
         """
         Prefetch overhead is related to IO. When it's larger than saved memory from
@@ -322,7 +325,7 @@ def promote_high_prefetch_overheaad_table_to_hbm(
 
         This function will end up updating proposal.
         """
-        if not self.enumerator:
+        if not enumerator:
             return
         what_if_hbm_proposal = copy.deepcopy(proposal)
         what_if_hbm_cached_tables = [
@@ -345,8 +348,8 @@ def promote_high_prefetch_overheaad_table_to_hbm(
             sharding_option.compute_kernel = EmbeddingComputeKernel.FUSED.value
 
         # appease pyre
-        assert self.enumerator
-        self.enumerator.populate_estimates(what_if_hbm_cached_tables)
+        assert enumerator
+        enumerator.populate_estimates(what_if_hbm_cached_tables)
 
         # Now what_if_hbm_proposal contain estimated storage for all HBM case. If
         # it's even smaller than offloaded case, we promote it to HBM
@@ -368,8 +371,8 @@ def promote_high_prefetch_overheaad_table_to_hbm(
         # In the end, update the storage cost for new proposal
 
         # appease pyre
-        assert self.enumerator
-        self.enumerator.populate_estimates(original_cached_tables)
+        assert enumerator
+        enumerator.populate_estimates(original_cached_tables)
 
     def propose(self) -> Optional[List[ShardingOption]]:
         return self.proposal
@@ -426,7 +429,9 @@ def feedback(
             self.starting_proposal, budget, self.enumerator
         )
         if self.proposal is not None:
-            self.promote_high_prefetch_overheaad_table_to_hbm(self.proposal)
+            self.promote_high_prefetch_overheaad_table_to_hbm(
+                self.enumerator, self.proposal
+            )
 
     @staticmethod
     def get_budget(proposal: List[ShardingOption], storage_constraint: Topology) -> int: