ARK reserved network paths for KV-cache transfers, cutting tail transfer time by up to 34 percent
AspireAI community · arXiv (cs.NI, cs.AI, cs.DC)
Disaggregated LLM inference splits prefill and decode across GPU pools, which produces enormous KV-cache transfers that last hundreds of milliseconds to seconds. At that scale they behave as elephant flows, and stateless ECMP hash collisions can overload one spine link while leaving others idle, stretching transfer times by seconds. ARK is a distributed path reservation mechanism that coordinates senders to pick source ports whose hashes map concurrent flows onto distinct spines, with no switch changes and no receiver-side packet reordering. Because these flows are long-lived, lightweight one-to-all coordination amortises over their lifetime. Packet-level RDMA simulations show ARK reduces mean and P95 flow completion time by up to 27.3 and 34.0 percent under moderate load, and further reduces mean time to first token by up to 12.9 percent. The results are simulation-based and published at SIGCOMM 2026.
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