Efficient Iterative Retrieval with Heterogeneous Batching

Dohyun Park, Hubertus Franke, Daniel G Waddington, Swaminathan Sundararaman, Yongjoo Park


Abstract
Modern information retrieval increasingly employs both embedding and generative models to handle complex queries. However, current serving systems suffer from low throughput and poor GPU utilization because they execute these models in isolation. Coarse-grained partitioning, such as dedicating GPUs to specific tasks, fails to adapt to dynamic workloads and creates computational “bubbles”. To address these, we present Orthrus, a serving system that performs heterogeneous batching within a single GPU kernel. The primary challenge lies in unifying embedding and generation workloads with conflicting computational patterns while optimizing batch composition for high performance. Orthrus addresses these challenges by employing incremental computing to match compute patterns and by adjusting batch composition in a workload-aware manner. Evaluation on four A100 GPUs shows that Orthrus achieves 1.28×–4.52× higher throughput and up to 52.0% lower latency than various deployment scenarios based on homogeneous batching, including those built on vLLM. We release our code at [https://github.com/illinoisdata/Orthrus](https://github.com/illinoisdata/Orthrus)
Anthology ID:
2026.emnlp-main.28
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
612–626
Language:
URL:
https://aclanthology.org/2026.emnlp-main.28/
DOI:
Bibkey:
Cite (ACL):
Dohyun Park, Hubertus Franke, Daniel G Waddington, Swaminathan Sundararaman, and Yongjoo Park. 2026. Efficient Iterative Retrieval with Heterogeneous Batching. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 612–626, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Efficient Iterative Retrieval with Heterogeneous Batching (Park et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.28.pdf