mlsanityData to 14 Oct 2026

CoDec: Prefix-Shared Decoding Kernel for LLMs

arXiv 2505.17694 ↗First posted 23 May 2025cs.LGcited by 4

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Abstract (arXiv)

Prefix-sharing among multiple prompts presents opportunities to combine the operations of the shared prefix, while attention computation in the decode stage, which becomes a critical bottleneck with increasing context lengths, is a memory-intensive process requiring heavy memory access on the key-value (KV) cache of the prefixes. Therefore, in this paper, we explore the potential of prefix-sharing in the attention computation of the decode stage. However, the tree structure of the prefix-sharing mechanism presents significant challenges for attention computation in efficiently processing shared KV cache access patterns while managing complex dependencies and balancing irregular workloads. To address the above challenges, we propose a dedicated attention kernel to combine the memory access of shared prefixes in the decoding stage, namely CoDec. CoDec delivers two key innovations: a novel shared-prefix attention kernel that optimizes memory hierarchy and exploits both intra-block and inter-block parallelism, and a comprehensive workload balancing mechanism that efficiently estimates cost, divides tasks, and schedules execution. Experimental results show that CoDec achieves an average 1.9× speedup and 120.9× memory access reduction compared to the state-of-the-art FlashDecoding kernel regarding attention computation in the decode stage and 3.8× end-to-end time per output token compared to the vLLM.

Key facts. Cited by 4 papers in the map (data through 14 Oct 2026). Builds on 33 of its 57 references that are in the map. First posted on arXiv 23 May 2025.

Builds on

33 of 57 references.

References · 33

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21 more
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Cited by year (2026 to 14 Oct)

Citing papers per year: 2025: 2; 2026: 2.

4 papers.

Similar, not cited

Close in wording, no citation either way

  1. 2025PAT: Accelerating LLM Decoding via Prefix-Aware Attention with Resource Efficient Multi-Tile Kernel
  2. 2025Hardware-Efficient Attention for Fast Decoding
  3. 2024Bifurcated Attention: Accelerating Massively Parallel Decoding with Shared Prefixes in LLMs
  4. 2026Where Activation Sparsity and KV-Cache Sparsity Cross in LLM Decoding
  5. 2026Salca: A Sparsity-Aware Hardware Accelerator for Efficient Long-Context Attention Decoding
  6. 2026SwiftKV: An Edge-Oriented Attention Algorithm and Multi-Head Accelerator for Fast, Efficient LLM Decoding
  7. 2026SAC: Disaggregated KV Cache System for Sparse Attention LLMs with CXL
  8. 2026Unifying Sparse Attention with Hierarchical Memory for Scalable Long-Context LLM Serving