Chamelio: A Fast Shared Cloud Network Stack for Isolated Tenant-Defined Protocols
Cloud providers need to offer programmable network stacks to tenants without sacrificing performance isolation, which Chamelio addresses by combining a shared fast path with runtime cycle accounting.
Chamelio introduces a programmable shared network stack for cloud tenants that supports tenant-defined protocols via a bounded eBPF fast path and tenant slow path, achieving 9.2 Mreq/s for TCP (matching hand-tuned TAS), reducing programmability tax from 23.9% to 3.8% via joint compilation, and bounding victim tail latency at 46 μs under adversarial conditions.
Conventional cloud network virtualization sends packets through multiple guest and host layers, inflating CPU cost and tail latency. Shared host datapaths collapse this layering into one optimized path across tenants, but existing shared stacks are fixed-function: tenants cannot specialize their protocols. eBPF is the natural vehicle for restoring programmability to a shared datapath, but today's extensions are hook-sized, and its verifier provides safety -- not performance isolation: one tenant's per-packet work can inflate every other tenant's tail latency. Chamelio is a programmable shared network stack that lets tenants implement full protocols through a bounded eBPF fast path and a tenant slow path, while approaching the performance and preserving the strong isolation of fixed shared stacks. It combines three ideas: a shared-stack architecture for tenant-defined protocols; joint optimisation of tenant handlers with provider infrastructure and co-resident tenants in the shared fast path; and a bounded fast path contract with runtime cycle accounting that keeps tenant programmability compatible with strong performance isolation. A tenant programmable TCP on Chamelio reaches 9.2 Mreq/s, matching the hand-tuned TAS stack; joint compilation shrinks the programmability tax from 23.9% to 3.8%; and under a scaling TCP adversary that drives uninstrumented stacks to 154 microseconds, Chamelio bounds victim tail latency at 46 microseconds.