Since its original implementation in the Linux kernel in 2018, Pressure Stall Information (PSI) has provided users with the high-fidelity signals needed to identify resource saturation before it becomes an outage. Unlike traditional utilization metrics, PSI tells the story of tasks stalled and time lost, all in nicely-packaged percentages of time across the CPU, memory, and I/O. With the recent release of Kubernetes v1.36, users across the ecosystem have a stable, reliable interface to observe resource contention at the node, pod, and container levels. In this post, we will dive into the improvements and performance testing that proved its readiness for production.