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arxiv: 2508.06526 · v3 · pith:EJJXK7XLnew · submitted 2025-08-02 · 💻 cs.DC · cs.AI· cs.AR

PiKV: KV Cache Management System for Mixture of Experts

Pith reviewed 2026-05-21 23:56 UTC · model grok-4.3

classification 💻 cs.DC cs.AIcs.AR
keywords KV cache managementMixture of Expertsdistributed inferencememory optimizationlarge language modelsparallel servingcache compression
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The pith

PiKV partitions KV caches across GPUs with expert-sharded storage and adaptive routing to lower memory and communication costs during MoE inference.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

Large-scale MoE models sparsify computation but still store dense KV caches that must stay synchronized across GPUs, creating a growing memory and communication bottleneck as context lengths increase. The paper presents PiKV as a framework that shards KV storage according to expert assignments, routes tokens to limit unnecessary cache accesses, schedules retention of only query-relevant entries, and adds compression modules inside the pipeline. A sympathetic reader cares because these changes would let models run longer contexts or larger scales on the same multi-GPU clusters without proportional rises in hardware or interconnect demand. The work is released as an open-source library positioned as an evolving system for comprehensive MoE KV management.

Core claim

The paper claims that expert-sharded KV storage partitions caches across GPUs to match MoE expert distribution, PiKV routing reduces token-to-KV access, PiKV Scheduling adaptively retains query-relevant entries, and PiKV Compression modules shrink memory usage, together cutting the memory and communication overhead that limits multi-GPU and multi-node inference for MoE architectures.

What carries the argument

Expert-sharded KV storage paired with PiKV routing, scheduling, and compression modules that distribute and selectively retain cache entries across GPUs.

If this is right

  • KV caches are partitioned across GPUs according to expert assignments rather than kept fully dense and synchronized.
  • Token-to-KV access volume drops through specialized PiKV routing that avoids unnecessary lookups.
  • Only query-relevant cache entries are retained by the adaptive PiKV Scheduling step.
  • Memory footprint shrinks further once PiKV Compression modules are integrated into the caching pipeline.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same sharding and selective-retention logic could apply to other sparse attention patterns if expert-like grouping can be identified in KV access.
  • Community extensions of the open-source library might add hardware-specific optimizations for particular interconnect topologies.
  • If the memory reductions hold at larger scales, fixed GPU clusters could support substantially longer context windows than current dense-cache limits allow.

Load-bearing premise

Expert-sharded storage combined with the proposed routing and scheduling will preserve model accuracy and acceptable latency while cutting memory and communication costs.

What would settle it

A side-by-side measurement of accuracy, end-to-end latency, peak memory usage, and inter-GPU communication volume on a standard MoE model using baseline dense KV caching versus the complete PiKV pipeline.

Figures

Figures reproduced from arXiv: 2508.06526 by Ben Lengerich, Dong Liu, Yanxuan Yu, Ying Nian Wu.

Figure 1
Figure 1. Figure 1: PiKV Framework there is huge demand to deploy sparsely-gated Mixture-of-Experts (MoE) structures [7, 12] to reduce computation costs at scale. However, serving such models introduces significant system￾level challenges. During inference, each token generation requires attending to the entire KV cache from prior tokens. For a 7B-scale MoE model with 128K context and 16 experts, the full KV cache can occupy … view at source ↗
Figure 2
Figure 2. Figure 2: KV cache memory usage comparison. Left: absolute [PITH_FULL_IMAGE:figures/full_fig_p002_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Latency performance comparison. Left: latency at [PITH_FULL_IMAGE:figures/full_fig_p002_3.png] view at source ↗
Figure 5
Figure 5. Figure 5: End-to-end performance comparison across dif [PITH_FULL_IMAGE:figures/full_fig_p007_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Long-context performance analysis. PiKV main [PITH_FULL_IMAGE:figures/full_fig_p008_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: Compression-accuracy trade-off analysis. PiKV’s [PITH_FULL_IMAGE:figures/full_fig_p008_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: Single Ablation Study of PiKV with 3 Key Compo [PITH_FULL_IMAGE:figures/full_fig_p008_8.png] view at source ↗
Figure 10
Figure 10. Figure 10: Memory analysis visualization. Top-left: Radar [PITH_FULL_IMAGE:figures/full_fig_p009_10.png] view at source ↗
Figure 9
Figure 9. Figure 9: Scalability Analysis of PiKV with Sequence Length [PITH_FULL_IMAGE:figures/full_fig_p009_9.png] view at source ↗
Figure 11
Figure 11. Figure 11: GPU utilization analysis. Top-left: 3D surface plot [PITH_FULL_IMAGE:figures/full_fig_p010_11.png] view at source ↗
Figure 13
Figure 13. Figure 13: Execution time analysis. Top-left: Donut chart [PITH_FULL_IMAGE:figures/full_fig_p011_13.png] view at source ↗
Figure 15
Figure 15. Figure 15: Communication analysis. Top-left: Chord diagram [PITH_FULL_IMAGE:figures/full_fig_p012_15.png] view at source ↗
read the original abstract

As large-scale language models continue to scale up in both size and context length, the memory and communication cost of key-value (KV) cache storage has become a major bottleneck in multi-GPU and multi-node inference. While MoE-based architectures sparsify computation across experts, the corresponding KV caches remain dense and globally synchronized, resulting in significant overhead. We introduce \textbf{PiKV}, a parallel and distributed KV cache serving framework tailored for MoE architecture. PiKV leverages \textit{expert-sharded KV storage} to partition caches across GPUs, \textit{PiKV routing} to reduce token-to-KV access, and a \textit{PiKV Scheduling} to adaptively retain query-relevant entries. To further reduce memory usage, PiKV integrates \textit{PiKV Compression} modules the caching pipeline for acceleration. PiKV is recently publicly available as an open-source software library: \href{https://github.com/NoakLiu/PiKV}{https://github.com/NoakLiu/PiKV}. PiKV is still a living project, aiming to become a comprehesive KV Cache management system for MoE Architectures.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 2 minor

Summary. The manuscript proposes PiKV, a parallel and distributed KV cache serving framework for Mixture of Experts (MoE) architectures. It describes expert-sharded KV storage to partition caches across GPUs, PiKV routing to reduce token-to-KV access, PiKV Scheduling to adaptively retain query-relevant entries, and PiKV Compression modules integrated into the caching pipeline. The system is released as an open-source library aimed at addressing memory and communication bottlenecks in multi-GPU, long-context MoE inference.

Significance. If the proposed components prove effective, PiKV could provide a practical approach to reducing KV cache overheads in scaled MoE serving without sacrificing accuracy or latency. The open-source release is a strength that enables reproducibility and further development. At present, however, the lack of supporting measurements leaves the practical significance unestablished.

major comments (1)
  1. Abstract: The central claims that expert-sharded KV storage, PiKV routing, PiKV Scheduling, and PiKV Compression together reduce memory/communication costs while maintaining acceptable accuracy and latency are presented without any experiments, benchmarks, ablations, or baseline comparisons. This is load-bearing for the contribution, as the manuscript supplies only high-level component descriptions and no data to confirm the design satisfies its necessary conditions under realistic MoE routing and long-context workloads.
minor comments (2)
  1. Abstract: The phrase 'integrates PiKV Compression modules the caching pipeline' is grammatically incomplete and should read 'integrates PiKV Compression modules into the caching pipeline'.
  2. Abstract: Typo 'comprehesive' should be corrected to 'comprehensive'.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the constructive feedback and the recommendation for major revision. We agree that empirical validation is essential to substantiate the claims about memory and communication reductions in PiKV. The revised manuscript will include comprehensive experiments, benchmarks, ablations, and baseline comparisons to address this gap.

read point-by-point responses
  1. Referee: Abstract: The central claims that expert-sharded KV storage, PiKV routing, PiKV Scheduling, and PiKV Compression together reduce memory/communication costs while maintaining acceptable accuracy and latency are presented without any experiments, benchmarks, ablations, or baseline comparisons. This is load-bearing for the contribution, as the manuscript supplies only high-level component descriptions and no data to confirm the design satisfies its necessary conditions under realistic MoE routing and long-context workloads.

    Authors: We agree that the current manuscript version presents the system design at a high level without quantitative results, which limits the ability to evaluate the practical impact. This was an oversight in the initial submission, as the focus was on describing the architecture of expert-sharded KV storage, PiKV routing, adaptive scheduling, and compression modules along with the open-source release. In the revised manuscript, we will add a dedicated experimental evaluation section. This will include benchmarks on multi-GPU MoE inference with long contexts, measuring KV cache memory footprint, inter-GPU communication volume, end-to-end latency, and accuracy retention against standard dense KV cache baselines. Ablation studies will isolate the contribution of each component (sharding, routing, scheduling, compression) under realistic MoE token routing patterns. The GitHub repository will be updated with the evaluation code and datasets for full reproducibility. revision: yes

Circularity Check

0 steps flagged

No significant circularity: architectural proposal without derivations or self-referential reductions

full rationale

The manuscript presents PiKV as a system architecture for KV cache management in MoE models, describing high-level components including expert-sharded KV storage to partition caches, PiKV routing to reduce token-to-KV access, PiKV Scheduling to retain query-relevant entries, and PiKV Compression modules. No equations, fitted parameters, predictions, or derivation chains appear in the provided text. The central claims concern the framework's design for reducing memory and communication costs; these are not shown to reduce to inputs by construction, nor do they rely on load-bearing self-citations or uniqueness theorems imported from prior author work. As a proposed software library and living project, the paper contains no mathematical or statistical steps that could exhibit the enumerated circularity patterns.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

As a systems paper the work rests on standard distributed-computing assumptions about GPU memory hierarchies and network costs; no free parameters or new physical entities are introduced.

axioms (1)
  • domain assumption Standard assumptions about memory access patterns and communication latency in multi-GPU clusters hold for MoE inference workloads.
    Implicit in the design of sharded storage and scheduling.

pith-pipeline@v0.9.0 · 5738 in / 1185 out tokens · 50173 ms · 2026-05-21T23:56:37.593025+00:00 · methodology

discussion (0)

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Reference graph

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