SieveServe: Adaptive Visual Token Pruning for Reliable and Efficient Multimodal LLM Inference

Xiao Li, Xiao Shi, Cheng Zhang, Sa Wang, Zhining Zhang, Xiaofang Zhao


Abstract
Efficient serving of multimodal large language models (MLLMs) is increasingly bottlenecked by high-resolution visual inputs, which can generate thousands of visual tokens per request and severely increase latency, memory pressure, and serving cost. Visual token pruning is a natural solution, but existing methods are difficult to deploy in production MLLM serving: many operate inside LLM layers and conflict with engine invariants such as KV-cache granularity, fused kernels, prefix caching, and batching, while fixed-ratio pruning can collapse accuracy on dense-information tasks such as document and chart understanding.

We present SieveServe, a serving-compatible framework for adaptive visual token pruning. SieveServe establishes pre-LLM vision-centric pruning as an engine-compatible paradigm and introduces a request-aware dual-guard policy: a Query Complexity Router (QCR) estimates query-side visual evidence demand, and a Dense Information Guard (DIG) detects image-side pruning risk using lightweight channel-wise embedding variance. Together, they allocate visual-token budgets per request, aggressively compressing pruning-robust inputs while conservatively preserving dense/high-risk ones.

Experiments with Qwen2.5-VL-7B and InternVL3-8B across eight benchmarks show that SieveServe retains at least 95% of baseline accuracy on all benchmarks and at least 97.8% on dense-information tasks, while compressing pruning-robust tasks by 3.2x and recovering over 20 accuracy points lost by fixed-ratio pruning. On high-resolution serving workloads, SieveServe reduces P90 TTFT by 5.4x and sustains 2.2-2.7x higher throughput under latency SLO constraints compared with vanilla vLLM.
Anthology ID:
2026.emnlp-main.648
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:
14918–14934
Language:
URL:
https://aclanthology.org/2026.emnlp-main.648/
DOI:
Bibkey:
Cite (ACL):
Xiao Li, Xiao Shi, Cheng Zhang, Sa Wang, Zhining Zhang, and Xiaofang Zhao. 2026. SieveServe: Adaptive Visual Token Pruning for Reliable and Efficient Multimodal LLM Inference. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 14918–14934, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
SieveServe: Adaptive Visual Token Pruning for Reliable and Efficient Multimodal LLM Inference (Li et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.648.pdf