Serving Hybrid LLM Loads with SLO Guarantees Using CPU-GPU Attention Piggybacking

Fuente: arXiv
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Main Authors: Mo, Zizhao, Chen, Junlin, Xu, Huanle, Xu, Chengzhong
Format: Preprint
Published: 2026
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author Mo, Zizhao
Chen, Junlin
Xu, Huanle
Xu, Chengzhong
author_facet Mo, Zizhao
Chen, Junlin
Xu, Huanle
Xu, Chengzhong
contents Nowadays, service providers often deploy multiple types of LLM services within shared clusters. While the service colocation improves resource utilization, it introduces significant interference risks for latency-sensitive (LS) services-which have strict SLO requirements for inference latency-and severely constrain the service capacity of best-effort (BE) services due to limited available memory. To address interference, existing systems typically rely on reserving headroom to constrain BE resource usage. However, this approach's coarse granularity compromises the SLO compliance of the latency-sensitive service and unnecessarily restricts the generation potential of the best effort service. In this paper, we propose OmniServe, a novel LLM serving system that efficiently harnesses both CPU and GPU resources to mitigate interference and improve throughput. Central to OmniServe is the Attention Piggybacking mechanism, which effectively offloads the Attention computation of BE services to CPUs on the fly. This mechanism also facilitates asynchronous communication between CPU and GPU streams, preventing GPUs from being blocked while aggregating Attention results. Additionally, OmniServe incorporates a dynamic batching control policy to adapt to fluctuating request arrivals, facilitating Dense module computation using layer-wise batching. Experimental results show that OmniServe improves the SLO attainment rate for LS services by up to $1.48\times$ while enhancing BE serving throughput by up to $9.85\times$ compared to state-of-the-art systems.
format Preprint
id arxiv_https___arxiv_org_abs_2603_12831
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Serving Hybrid LLM Loads with SLO Guarantees Using CPU-GPU Attention Piggybacking
Mo, Zizhao
Chen, Junlin
Xu, Huanle
Xu, Chengzhong
Distributed, Parallel, and Cluster Computing
Nowadays, service providers often deploy multiple types of LLM services within shared clusters. While the service colocation improves resource utilization, it introduces significant interference risks for latency-sensitive (LS) services-which have strict SLO requirements for inference latency-and severely constrain the service capacity of best-effort (BE) services due to limited available memory. To address interference, existing systems typically rely on reserving headroom to constrain BE resource usage. However, this approach's coarse granularity compromises the SLO compliance of the latency-sensitive service and unnecessarily restricts the generation potential of the best effort service. In this paper, we propose OmniServe, a novel LLM serving system that efficiently harnesses both CPU and GPU resources to mitigate interference and improve throughput. Central to OmniServe is the Attention Piggybacking mechanism, which effectively offloads the Attention computation of BE services to CPUs on the fly. This mechanism also facilitates asynchronous communication between CPU and GPU streams, preventing GPUs from being blocked while aggregating Attention results. Additionally, OmniServe incorporates a dynamic batching control policy to adapt to fluctuating request arrivals, facilitating Dense module computation using layer-wise batching. Experimental results show that OmniServe improves the SLO attainment rate for LS services by up to $1.48\times$ while enhancing BE serving throughput by up to $9.85\times$ compared to state-of-the-art systems.
title Serving Hybrid LLM Loads with SLO Guarantees Using CPU-GPU Attention Piggybacking
topic Distributed, Parallel, and Cluster Computing
url https://arxiv.org/abs/2603.12831