Hybrid Core Allocation: From Overallocation to Reliable Sharing

What this post added

This post introduces a significant evolution in Uber's CPU resource allocation strategy within its Odin container orchestration system. It details the transition from dedicated CPU allocation to a hybrid model that incorporates shared cores alongside dedicated ones. Key contributions include the introduction of shared core pooling, over-allocation control, fair contention handling via `cpu.shares`, and an upgraded vertical scaler. The post also discusses NUMA considerations for optimal CPU and memory affinity, the implementation of in-place vertical scaling for stateful workloads, and how Odin bridges Kubernetes gaps for hybrid core allocation. The core innovation is enabling more intelligent handling of bursty CPU usage patterns, leading to improved performance, reliability, and cost-effectiveness for colocated workloads.