Prepare to enable Linux pressure stall information on Red Hat OpenShift

Linux pressure stall information (PSI) can be enabled in Red Hat OpenShift 4.21 via a MachineConfig object, exposing CPU, memory, and I/O stall metrics at the node, pod, and container level. Unlike traditional utilization metrics, PSI reveals actual resource contention and stalled work. Performance testing with 500+ containers shows no measurable impact on kubelet CPU or memory, but Prometheus pod RSS increases by up to 1.3 GB (42% above baseline) due to higher metric cardinality. Each pod generates 18 PSI metric series (3 container types × 6 metric types), including pause and POD cgroup containers. Metric relabeling to drop non-application container PSI series could reduce Prometheus memory, but this configuration is currently unsupported in OpenShift's built-in cluster monitoring operator. Recommendations include pre-allocating an additional 1.4 GB RSS per Prometheus pod before enabling PSI in production.