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Kubernetes v1.36: PSI Metrics for Kubernetes Graduates to GA
Kubernetes v1.36 has graduated Pressure Stall Information (PSI) metrics to general availability, providing crucial signals for identifying CPU, memory, and I/O resource saturation at the node, pod, and container levels.
What: Maria Fernanda Romano Silva announced on May 12, 2026, that Kubernetes v1.36 now includes Pressure Stall Information (PSI) metrics, a Linux kernel feature since 2018, as generally available. This offers high-fidelity data on tasks stalled and time lost due to resource contention, complementing traditional utilization metrics. Extensive performance testing confirmed its production readiness on high-density workloads.
Why it matters: PSI metrics offer a more precise way to diagnose performance bottlenecks by indicating *why* a system is slow (resource contention) rather than just *what* its utilization is. This moves Kubernetes monitoring beyond simplistic utilization percentages to actionable insights for preventing outages.
Takeaway: Ensure your Kubernetes nodes are running Linux kernel 4.20+ with cgroup v2 and `CONFIG_PSI=y` to leverage the generally available PSI metrics from `/metrics/cadvisor` or the Summary API for advanced resource monitoring.
Deep dive
- Pressure Stall Information (PSI) metrics, a Linux kernel feature since 2018, have graduated to General Availability (GA) in Kubernetes v1.36, as announced by Maria Fernanda Romano Silva of Google Cloud.
- PSI provides high-fidelity signals for identifying resource saturation (CPU, memory, I/O) by showing the absolute time tasks spend stalled and 10s, 60s, and 300s moving averages, offering more insight than traditional utilization metrics.
- The metrics are available at the node, pod, and container levels, helping operators identify and address resource contention before it leads to outages.
- Extensive performance testing by SIG Node on high-density workloads (80+ pods) confirmed that Kubelet's collection of PSI metrics is highly lightweight, adding negligible overhead (around 0.1 cores or 2.5% of total node capacity).
- The underlying kernel-level overhead of enabling PSI was also found to be minimal (0.037 to 0.125 cores, or 0.925%-3.125% of total node capacity).
- Improvements between beta (v1.34) and stable (v1.36) include smarter metric emission, where the Kubelet now detects underlying OS PSI support before reporting, preventing misleading zero-valued metrics.
- To utilize PSI, Kubernetes nodes must be running Linux kernel version 4.20 or later, use cgroup v2, and have PSI enabled at the OS level (kernel compiled with
CONFIG_PSI=yand not booted withpsi=0). - Once prerequisites are met, PSI metrics can be collected and visualized by scraping the
/metrics/cadvisorendpoint with a Prometheus-compatible solution or by querying the Summary API.
Decoder
- Pressure Stall Information (PSI): A Linux kernel feature that provides real-time metrics on how much time processes spend waiting for CPU, memory, or I/O resources due to contention, indicating resource saturation rather than just utilization.
- cgroup v2: The second version of the Linux control group interface, which provides a unified hierarchy for managing and monitoring system resources for groups of processes.
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