cuDNN Benchmark Memory
cuDNN benchmark mode can use more memory for algorithm search, and not all algorithms work with all configs.
cuDNN benchmark mode can use more memory for algorithm search, and not all algorithms work with all configs.
What this failure is
cuDNN Benchmark Memory is a Memory failure seen during ML training runs. cuDNN benchmark mode can use more memory for algorithm search, and not all algorithms work with all configs. Common tags: Cudnn, Benchmark, Memory, Performance.
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Why it happens (the mechanism)
CuDNN benchmark tries multiple algorithms using memory. Algorithm not available for specific tensor layout. Variable input sizes trigger re-benchmark. CuDNN doesn't support some custom operations. Taken together, these mechanisms explain why the failure is reproducible, why it tends to surface on specific workloads or scales, and why generic mitigation attempts often fall short without addressing the underlying cause.
What you'll observe
- cuDNN benchmark causes OOM
- cuDNN not using optimal algorithm
- cuDNN determinism warnings
Common symptoms and what they mean
| Symptom | Why it happens |
|---|---|
| First iterations are slow with cudnn.benchmark=True | cuDNN benchmark tries multiple algorithms using memory |
| Memory grows during cuDNN algorithm search | Algorithm not available for specific tensor layout |
| cuDNN algorithm not found for specific config | Variable input sizes trigger re-benchmark |
Which systems are affected
- Training with cuDNN benchmark for performance
- CNN training with cuDNN optimization
- Variable input size CNNs
How to confirm this is the problem
Use this checklist to test the hypothesis against a small reproduction. No single line proves the root cause, so preserve the preceding events and compare one variable at a time.
- ✓Reproduce the failure from a clean checkpoint/seed: the symptom must appear without warm-up state from a previous run.
- ✓Verified signal present: First iterations are slow with cudnn.benchmark=True
- ✓Verified signal present: Memory grows during cuDNN algorithm search
- ✓Verified signal present: cuDNN algorithm not found for specific config
- ✓A targeted fix from the "How to fix it" section eliminates or substantially reduces the symptom within one validation pass.
The fix and the prevention pattern
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Diagnose this failure in VS Code
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Root cause
- cuDNN benchmark tries multiple algorithms using memory
- Algorithm not available for specific tensor layout
- Variable input sizes trigger re-benchmark
- cuDNN doesn't support some custom operations
The fix and how to prevent it
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