Skip to content
Book Open access

PKAS: Predictive KVCache-Aware Scheduling for Faster LLM and Transformer Inferences

Jul 2026 · IEEE International Symposium on High-Performance Parallel Distributed Computing · 1 citation · 40 references
Computer Science

Abstract

With rising popularity of LLMs, the performance, scalability, and resource-efficiency of inferences become a crucial challenge. The core part of the inference process is the KV cache, which avoids recomputing intermediate attention states, and the batching strategy that batches multiple requests per forward pass to leverage GPU parallelism. KV cache memory grows linearly with sequence length and batch sizes, easily exceeding the limited GPU memory capacity. State-of-the-art inference runtimes use continuous batching to maximize GPU utilization by interleaving the processing of new requests (i.e., prefill requests) with ongoing generation requests (i.e., decode requests). However, existing schedulers greedily admit prefill requests without considering the future KV cache memory required to successfully run the decode phases. This shortsighted approach causes frequent KV cache overflows, which in turn trigger preemption and recomputation of requests, severely degrading both throughput and latency. We propose PKAS, a Predictive KV Cache-Aware Scheduling algorithm to mitigate this inefficiency by reducing preemptions. PKAS uses a low-overhead technique to simulate future KV cache utilization and guide the admissibility for new request candidates. Combined with lightweight output-length predictions, PKAS can make better batching decisions, preventing KV cache overflows and drastically reducing preemptions. Evaluations on diverse models and workloads show that PKAS achieves up to 7.34x higher throughput and 8x lower latency compared to state-of-the-art scheduling, with the largest gains on long-context workloads where KV cache pressure is high.

Read PDF

Similar papers

Preprint Jul 2026

DualDecoder: Accelerate Long Context LLM Inference by Predictive Prefetch

Long-context inference is becoming a fundamental capability for modern LLM serving, especially driven by emerging agentic applications. Yet it faces a severe memory wall that the KV cache scales proportionally with increasing context length and request concurrency. Existing sparse KV cache methods offload most KV entries to host memory and retrieve only the critical KV entries needed by each decoding step. However, they commonly introduce substantial auxiliary states in GPU memory for KV retrieval management. Our measurements show that these often-overlooked auxiliary states introduce significant memory overhead and become a new bottleneck under high-concurrency workloads. In this paper, we present DualDecoder, a lightweight serving system for long-context LLM inference that enables efficient sparse KV cache retrieval from host memory. Our key insight is that the critical KV entries required for decoding the next token can be accurately predicted from the preceding speculated token. This predictability enables KV retrieval to be proactively prefetched and overlapped with decoding computation, effectively eliminating the GPU memory overhead of auxiliary states. To achieve this prefetching efficiently, DualDecoder leverages a novel dual-token decoding pipeline that accurately identifies critical KV entries with negligible computational overhead, and designs a layer-aware transfer schedule to overlap KV prefetching with model computation and a layer-scoped memory manager to reduce the GPU runtime buffer. Experimental results show that DualDecoder improves decoding throughput by up to 2.62$\times$ over state-of-the-art systems while preserving decoding latency and model quality.

Zuning Liang, Zhiyi Yao, Qi Chen et al. · 0 citations
Preprint Aug 2026

OasisKV: Scaling In-Decode KV Cache Beyond HBM with Lookahead Sparse Prefetching

OasisKV is presented, a memory-centric LLM inference system design that alleviates HBM capacity pressure by decoupling full KV-cache storage from HBM during LLM decoding and observes that future important tokens can be predicted accurately in advance using lookahead tokens drafted by speculative decoding (SD).

Can Xiao, Sukmin Cho, Junbong We et al. · 0 citations
Sep 2026

Co-Optimizing Request Scheduling and KV Caching for Edge LLM Serving

Deploying large language models (LLMs) on edge nodes enables low-latency and privacy-preserving inference, but faces severe resource constraints under high-concurrence workloads. While existing inference systems leverage intranode key–value (KV) caching to improve efficiency, they largely neglect the unique complexities of multinode edge environments. Specifically, reactive KV cache eviction policies suffer from temporal uncertainty, often discarding reusable KV caches prematurely, while the tight coupling between request scheduling and cache placement often leads to myopic decisions that exacerbate load imbalance and resource contention. To address these challenges, we propose a dynamic block-level paradigm that treats KV blocks as the fundamental units for caching and scheduling, enabling dynamic sharing, generation, and eviction of arbitrary-length prefixes. We present complete modeling of the spatiotemporal coupling between scheduling and caching under block-level granularity, capturing intricate interactions overlooked by prior work. Based on this model, we design an online joint optimization algorithm, which applies to general edge LLM serving scenarios. The algorithm decouples spatiotemporal dependencies via randomized rounding over per-slot subproblems, achieving a balance between real-time responsiveness and long-term system efficiency. Theoretical analysis establishes high-probability near-optimality guarantees, and extensive experiments show that our method reduces the average time to first token (TTFT) by up to 54.02% over existing baselines.

Xishuo Li, Wei Jiao, Jun He et al. · 0 citations
Conference Jul 2026

Dynamic Pipeline Inference Optimization for LLMs: Load-Aware Partitioning, Updating, and Migration

With the rapid advancement of deep learning technology, the parameter scale of large language models has grown exponentially, expanding from hundreds of millions in the early stages to hundreds of billions or even trillions today. Pipeline inference is a crucial approach enabling efficient inference in large language models. However, existing pipeline inference relies on static layer allocation, ignoring the intrinsic variance in layer-wise computation and memory footprints, as well as runtime fluctuations in request rates and sequence lengths. Consequently, under dynamic workloads, compute-dense stages rapidly bottleneck the pipeline and induce severe queue blocking while leaving other devices idle, ultimately degrading end-to-end latency and severe GPU underutilization. To address these challenges, this paper proposes a dynamic pipeline parallel inference algorithm. Centering on the three phases of LLM pipeline inference—partitioning, updating, and migration—the algorithm introduces: (1) A proactive update trigger mechanism driven by multidimensional load forecasting. Rather than relying on reactive bottleneck indicators, it translates projected request rates and token lengths into stage-level VRAM demands, preemptively initiating reconfiguration only when impending hardware capacity violations are detected; (2) A joint partition-migration optimization strategy utilizing a two-stage biased random key genetic algorithm. By embedding a maximum-weight bipartite matching formulation into the evolutionary fitness evaluation, this strategy mathematically couples pipeline boundary search with physical state mapping, maximizing resident parameter reuse to guarantee minimal-overhead model migration; (3) Distributed cluster experiments conducted using public datasets and the Ray framework demonstrate that the proposed method outperforms existing state-of-the-art pipeline inference solutions in metrics including response latency and resource overhead, specifically improving throughput by 2.3% compared to the SOTA framework.

Ying-Xin Wang, Binbin Feng, Zhijun Ding · 0 citations
Conference Jul 2026

Pegasus: Accelerating Large Language Model Inference with Stateful Prefix Caching

Modern large language model (LLM) inference suffers from severe Time-To-First-Token (TTFT) bottlenecks. Existing prefix KV caching mechanisms are inherently stateless, forcing a trade-off between cross-chunk attention accuracy and online recomputation overhead. To address this issue, we propose Pegasus, a novel stateful prefix KV caching system that aims to achieve full-context attention accuracy while avoiding costly recomputation. To handle the exponential growth of context states under limited memory capacity, Pegasus employs a Recursive Path-Pruning Caching (RPPC) algorithm to selectively cache high-value states based on access frequency, memory footprint, and asymmetric latency benefit. In addition, Pegasus introduces a transition-based KV management mechanism to mitigate cache-miss overhead. By exploiting the sparsity of state-dependent KV variations, it replaces expensive attention recomputation and I/O-intensive tensor reloading with lightweight sparse state transitions. Extensive experiments show that Pegasus improves end-to-end serving throughput by 45.9% on average, reduces TTFT by up to 78.5%, and lowers cache-miss recovery overhead by more than 72%.

Fahao Chen, Peng Li, Dongxiao Yu et al. · 0 citations