RouteNLP: Closed-Loop LLM Routing with Conformal Cascading and Distillation Co-Optimization

Fuente: arXiv
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Auteurs principaux: Guo, Dongxin, Wu, Jikun, Yiu, Siu Ming
Format: Preprint
Publié: 2026
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author Guo, Dongxin
Wu, Jikun
Yiu, Siu Ming
author_facet Guo, Dongxin
Wu, Jikun
Yiu, Siu Ming
contents Serving diverse NLP workloads with large language models is costly: at one enterprise partner, inference costs exceeded $200K/month despite over 70% of queries being routine tasks well within the capability of smaller models. We present RouteNLP, a closed-loop framework that routes queries across a tiered model portfolio to minimize cost while satisfying per-task quality constraints. The framework integrates three components: a difficulty-aware router with shared task-conditioned representations trained on preference data and quality signals; confidence-calibrated cascading that uses conformal prediction for distribution-free threshold initialization; and a distillation-routing co-optimization loop that clusters escalation failures, applies targeted knowledge distillation to cheaper models, and automatically retrains the router, yielding over twice the cost improvement of untargeted distillation. In an 8-week pilot deployment processing ~5K queries/day at an enterprise customer-service division, RouteNLP reduced inference costs by 58% while maintaining 91% response acceptance and reducing p99 latency from 1,847 ms to 387 ms. On a six-task benchmark spanning finance, customer service, and legal domains, the framework achieves 40-85% cost reduction while retaining 96-100% quality on structured tasks and 96-98% on generation tasks, with human evaluation confirming that 74.5% of routed generation outputs match or exceed frontier-model quality.
format Preprint
id arxiv_https___arxiv_org_abs_2604_23577
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle RouteNLP: Closed-Loop LLM Routing with Conformal Cascading and Distillation Co-Optimization
Guo, Dongxin
Wu, Jikun
Yiu, Siu Ming
Computation and Language
Machine Learning
I.2.7; I.2.6; H.3.3; C.4
Serving diverse NLP workloads with large language models is costly: at one enterprise partner, inference costs exceeded $200K/month despite over 70% of queries being routine tasks well within the capability of smaller models. We present RouteNLP, a closed-loop framework that routes queries across a tiered model portfolio to minimize cost while satisfying per-task quality constraints. The framework integrates three components: a difficulty-aware router with shared task-conditioned representations trained on preference data and quality signals; confidence-calibrated cascading that uses conformal prediction for distribution-free threshold initialization; and a distillation-routing co-optimization loop that clusters escalation failures, applies targeted knowledge distillation to cheaper models, and automatically retrains the router, yielding over twice the cost improvement of untargeted distillation. In an 8-week pilot deployment processing ~5K queries/day at an enterprise customer-service division, RouteNLP reduced inference costs by 58% while maintaining 91% response acceptance and reducing p99 latency from 1,847 ms to 387 ms. On a six-task benchmark spanning finance, customer service, and legal domains, the framework achieves 40-85% cost reduction while retaining 96-100% quality on structured tasks and 96-98% on generation tasks, with human evaluation confirming that 74.5% of routed generation outputs match or exceed frontier-model quality.
title RouteNLP: Closed-Loop LLM Routing with Conformal Cascading and Distillation Co-Optimization
topic Computation and Language
Machine Learning
I.2.7; I.2.6; H.3.3; C.4
url https://arxiv.org/abs/2604.23577