⚡️ Speed up method MemoryAttentionLayer._forward_ca by 7%
#51
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
📄 7% (0.07x) speedup for
MemoryAttentionLayer._forward_cainultralytics/models/sam/modules/memory_attention.py⏱️ Runtime :
1.29 milliseconds→1.20 milliseconds(best of14runs)📝 Explanation and details
The optimized code achieves a 7% speedup by eliminating redundant computations and reducing unnecessary tensor operations in the cross-attention mechanism.
Key optimizations applied:
Eliminated redundant normalization computation: The original code computed
self.norm2(tgt)and then immediately used it in conditional expressions within the attention call. The optimized version computestgt2_normed = self.norm2(tgt)once and reuses it, avoiding duplicate normalization operations.Conditional tensor addition only when needed: Instead of always performing tensor additions like
tgt2 + query_posandmemory + posregardless of whether positional encodings are enabled, the optimized version uses explicit conditionals to only perform additions when the respective flags are True and the positional tensors are not None. This saves unnecessary tensor arithmetic operations.Reduced intermediate variable creation: The optimized version pre-computes the
qandktensors based on the positional encoding flags, then passes them directly tocross_attn_image(), reducing the number of temporary tensor objects created during execution.Performance impact analysis:
From the line profiler results, the most expensive operations are
norm2(tgt)(28.6% of runtime) andcross_attn_image()calls (38.7% of runtime). By eliminating redundant normalization and reducing tensor operations before the attention call, the optimization directly targets these hotspots.Test case benefits:
The annotated tests show the optimization is particularly effective for scenarios with positional encoding disabled (
test_forward_ca_no_positional_encodingshows 11.2% improvement), indicating the conditional logic provides the most benefit when unnecessary tensor operations can be completely avoided.The optimization maintains identical behavior while reducing computational overhead, making it especially valuable for inference workloads where this attention layer may be called frequently.
✅ Correctness verification report:
🌀 Generated Regression Tests and Runtime
To edit these changes
git checkout codeflash/optimize-MemoryAttentionLayer._forward_ca-mirduejgand push.