Research map / Large language models / Reasoning and chain of thought
Online Cascade Learning for Efficient Inference over Streams
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Proposes online cascade learning, which trains a cascade of small models (logistic regression, BERT) online by imitating an LLM expert and learns deferral policies jointly, cutting LLM inference cost by up to 90% while matching LLM accuracy on four stream classification benchmarks.
Problem
LLM inference over data streams is too expensive, and existing cascade and distillation methods require a pre-labeled training set, making them unsuitable for streaming settings.
Approach
Formulates learning a model cascade with deferral policies as an episodic MDP that trades prediction loss against deferral cost, and learns it fully online by imitation of the LLM expert (DAgger-style with decaying jump probability), with calibrated MLP deferral functions and a no-regret OGD guarantee.
Key results
- On IMDB with GPT-3.5 Turbo as LLM, online cascade learning reaches 93.01% accuracy at N=5200 LLM calls vs. 94.15% for GPT-3.5 Turbo, saving about 60% of LLM calls.
- On HateSpeech (N=507), the cascade achieves 82.66% accuracy and 82.36% recall vs. GPT-3.5 Turbo's 83.34% and 83.28%, cutting LLM inference costs by over 90%.
- With Llama 2 70B Chat on FEVER at N=2800, the cascade slightly outperforms the LLM (77.73% vs. 77.15% accuracy).
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Add learned deferral policy to online ensemble learning (ablation) | Online Cascade Learning · IMDB | accuracy: 88.80 -> 92.48 | Helped |
| Add learned deferral policy to online ensemble learning (ablation) | Online Cascade Learning · HateSpeech, N=2700 | accuracy: 77.48 -> 85.35 | Helped |
| Add learned deferral policy to online ensemble learning (ablation) | Online Cascade Learning · ISEAR, N=2700 | accuracy: 61.78 -> 69.75 | Helped |
| Add learned deferral policy to online ensemble learning (ablation) | Online Cascade Learning · FEVER, N=700 | accuracy: 61.69 -> 61.95 | No clear effect |
| Use Llama 2 70B Chat instead of GPT-3.5 Turbo as the cascade LLM | Online Cascade Learning · HateSpeech, N=4900 | accuracy: 83.26 -> 78.32 | Mixed |
| Use a larger cascade with BERT-large | Online Cascade Learning · HateSpeech | accuracy | Hurt |
| Process IMDB reviews in ascending input-length order | Online Cascade Learning · IMDB, GPT-3.5 Turbo cascade | average accuracy: 90.77% -> 90.23%; -0.54% | Hurt |
| Process IMDB reviews in ascending input-length order | Online Cascade Learning · IMDB, Llama 2 70B cascade | average accuracy: 90.97% -> 90.64%; -0.33% | Hurt |
| Put Comedy reviews in the last part of the IMDB stream | Online Cascade Learning · IMDB, GPT-3.5 Turbo cascade | average accuracy: 90.77% -> 90.85%; +0.08% | Helped |
| Put Comedy reviews in the last part of the IMDB stream | Online Cascade Learning · IMDB, Llama 2 70B cascade | average accuracy: 90.97% -> 91.46%; +0.49% | Helped |
Surprising findings
- On ISEAR, the cascade with Llama 2 70B Chat surpasses the standalone LLM as cost budget grows, since small models learn from LLM annotations.
- Confidence-based deferral rules are reported to be inadequate for online cascades with noisy LLM annotations, motivating learned deferral functions.
Limitations
- Cascade size must be matched to task complexity; a larger cascade with BERT-large degraded HateSpeech performance.
- Cost model assumes uniform inference cost per model and uses FLOPs estimates rather than measured wall-clock costs for GPT-3.5 Turbo.
- Evaluated only on four binary or small-class text classification benchmarks.
Experimental setup
Datasets: IMDB HateSpeech ISEAR FEVER
Benchmarks: IMDB HateSpeech ISEAR FEVER
Metrics: accuracy recall F1 inference cost (LLM calls)
Baselines: GPT-3.5 Turbo Llama 2 70B Chat Distilled LR Distilled BERT-base Online Ensemble Learning
Builds on: DAgger knowledge distillation online gradient descent
Closest papers by meaning
- C3PO: Optimized Large Language Model Cascades with Probabilistic Cost Constraints for Reasoning (NeurIPS 2025 · similarity 0.90)
- Large Language Model Cascades with Mixture of Thought Representations for Cost-Efficient Reasoning (ICLR 2024 · similarity 0.89)
- Cascaded Language Models for Cost-Effective Human–AI Decision-Making (NeurIPS 2025 · similarity 0.88)
- Cascadia: An Efficient Cascade Serving System for Large Language Models (ICLR 2026 · similarity 0.87)
- Online Adaptation of Language Models with a Memory of Amortized Contexts (NeurIPS 2024 · similarity 0.87)
- Language Model Cascades: Token-Level Uncertainty And Beyond (ICLR 2024 · similarity 0.86)
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