⚡️ Speed up function get_cdn_group by 6%
#53
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📄 6% (0.06x) speedup for
get_cdn_groupinultralytics/models/utils/ops.py⏱️ Runtime :
9.05 milliseconds→8.51 milliseconds(best of216runs)📝 Explanation and details
The optimized code delivers a 6% speedup through several targeted micro-optimizations focused on reducing tensor operations and improving memory access patterns.
Key Optimizations Applied:
Vectorized Array Operations in
xyxy2xywh: Replaced four individual element assignments with two vectorized slice operations (y[..., 0:2] = (x[..., 0:2] + x[..., 2:4]) / 2andy[..., 2:4] = x[..., 2:4] - x[..., 0:2]). This reduces the number of indexing operations from 4 to 2, improving cache locality and reducing overhead.Explicit Device Placement: Added
device=parameters totorch.rand,torch.randint, andtorch.arangecalls to avoid potential device transfers. This eliminates unnecessary memory movements between CPU/GPU that can cause performance bottlenecks.Optimized Index Generation: Replaced Python list comprehensions with direct
torch.arangecalls on the target device for creatingmap_indices, reducing Python loop overhead and ensuring tensors are created on the correct device from the start.Improved Tensor Methods: Changed
torch.nonzero(mask).squeeze(-1)tomask.nonzero(as_tuple=True)[0]andclip_toclamp_for better performance with newer PyTorch versions.Eliminated Unnecessary Device Transfers: Removed
.to(class_embed.device)calls in the return statement since tensors are now created on the correct device initially.Performance Impact: These optimizations are particularly effective for this function since it's called during neural network training in the forward pass (as shown in the function_references). The 6% improvement compounds across training batches, and the test results show consistent speedups across various batch sizes and configurations, with larger improvements (8-12%) on more complex scenarios involving larger batches or higher denoising query counts.
The optimizations maintain identical functionality while reducing memory allocation overhead and tensor operation counts, which is especially valuable in GPU-accelerated training scenarios where memory bandwidth and kernel launch overhead are critical bottlenecks.
✅ Correctness verification report:
🌀 Generated Regression Tests and Runtime
To edit these changes
git checkout codeflash/optimize-get_cdn_group-mirftbq4and push.