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abstract indexed · arXiv 2607.25291 · updated 2026-10-18

CoSA: Accelerating Long-Context Inference via Proxy-Kernel Co-Designed Sparse Attention

First page of CoSA: Accelerating Long-Context Inference via Proxy-Kernel Co-Designed Sparse Attention
From the original paper · arXiv 2607.25291Page 1. Select the image to read the PDF.

CoSA replaces dense self-attention (and prior two-stage proxy-mask sparse attention) with a kernel-aware proxy that orders KV page visits and an ordered-skipping kernel that drops additional blocks online using softmax statistics, all training-free. It costs integration of a custom attention kernel (distributed via Tencent AngelSlim), adds proxy-selection overhead per query, and requires no retraining or extra memory beyond standard paged KV cache. Under tight compute budgets the proxy can still drop salient blocks, and online skipping driven by softmax statistics risks compounding recall errors on workloads whose attention patterns differ from the evaluated benchmarks, so accuracy must be validated per model and task.

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What you would change

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Compare against

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What to measure

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Why it was shortlisted

The technical change, research area, and reason it entered the archive.

recommendation
test
research area
attention and kernels
technical change
Proxy-kernel co-designed block-sparse attention (CoSA)
published
2026-07-28

The method is training-free and targets exactly the 24 GB single-GPU long-context prefill bottleneck, but it depends on a custom kernel whose accuracy benefits at tight budgets must be verified on the reader's specific models and workloads before production adoption.

About the technical core

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Claims and evidence

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  1. claim 01Paperraft inference
    Read the brief interpretation

    CoSA replaces dense self-attention (and prior two-stage proxy-mask sparse attention) with a kernel-aware proxy that orders KV page visits and an ordered-skipping kernel that drops additional blocks online using softmax statistics, all training-free. It costs integration of a custom attention kernel (distributed via Tencent AngelSlim), adds proxy-selection overhead per query, and requires no retraining or extra memory beyond standard paged KV cache. Under tight compute budgets the proxy can still drop salient blocks, and online skipping driven by softmax statistics risks compounding recall errors on workloads whose attention patterns differ from the evaluated benchmarks, so accuracy must be validated per model and task.

    This is a Paperraft inference. It is not pinned to a verified PDF passage.

    Inspect the source
  2. claim 02Paperraft inference

    4.93x attention speedup and 2.53x lower end-to-end Time-to-First-Token at 128K context with negligible performance degradation

    This is a Paperraft inference. It is not pinned to a verified PDF passage.

    Inspect the source

Exposure map

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quality

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compute and memory

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latency

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operations

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software compatibility

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security

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data and training

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reproducibility

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Continue the investigation

A reading guide for attention and kernels.

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What to inspect

Which tensor shapes, precision settings, and hardware support the reported kernel result?

Plan a fair comparison

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Questions for adoption

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Inside the paper

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Provisional research brief updated 2026-10-18. Paperraft has not reproduced this experiment.

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arXiv 2607.25291

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