Jerry's technical notesNotes on Kubernetes, cloud platforms, and self-hosted services.https://jerrytech.me/enCPU is only 30% used, so why is it throttled? Inside the 100ms quota of a CPU limithttps://jerrytech.me/en/blog/2026/09/26/kubernetes-cpu-limit-throttling/https://jerrytech.me/en/blog/2026/09/26/kubernetes-cpu-limit-throttling/A developer reports high latency, but the CPU on the dashboard looks idle. Follow the 100ms cgroup quota to see how a CPU limit is enforced on the Node, and what to do about it.Sat, 26 Sep 2026 00:00:00 GMTHands-on: reproduce "only 30% CPU, yet throttled" in kindhttps://jerrytech.me/en/blog/2026/09/26/kubernetes-cpu-limit-throttling-lab/https://jerrytech.me/en/blog/2026/09/26/kubernetes-cpu-limit-throttling-lab/Read cpu.max and cpu.stat in a throwaway local cluster, build a service that gets throttled by groups of requests, then measure GOMAXPROCS, adding replicas, raising the limit, cpu.weight, and what changes on a busy Node.Sat, 26 Sep 2026 00:00:00 GMTWhere does a new Pod run? How the Scheduler decides and hands offhttps://jerrytech.me/en/blog/2026/09/26/kubernetes-pod-scheduling/https://jerrytech.me/en/blog/2026/09/26/kubernetes-pod-scheduling/A new replica stays Pending while the CPU sits idle. Break down the Scheduler's filtering, scoring, and assignment to find what is blocking it.Sat, 26 Sep 2026 00:00:00 GMTHands-on: reproduce an unschedulable Pod in kind and test five fixeshttps://jerrytech.me/en/blog/2026/09/26/kubernetes-pod-scheduling-lab/https://jerrytech.me/en/blog/2026/09/26/kubernetes-pod-scheduling-lab/Build the "idle CPU, but the new replica is Pending" state in a throwaway local cluster, read FailedScheduling, then see where each fix sends the Pod.Sat, 26 Sep 2026 00:00:00 GMTHow does a Deployment become Pods? Reconcile through two controllershttps://jerrytech.me/en/blog/2026/09/21/kubernetes-deployment-reconcile/https://jerrytech.me/en/blog/2026/09/21/kubernetes-deployment-reconcile/Follow the work of two controllers, from Watch and local caches to work queues and rolling updates.Mon, 21 Sep 2026 00:00:00 GMTHow Kubernetes works: from the API to containershttps://jerrytech.me/en/blog/2026/09/21/kubernetes-reading-map/https://jerrytech.me/en/blog/2026/09/21/kubernetes-reading-map/For readers who know basic Kubernetes operations and want to understand controllers, scheduling, resource management, and containers.Mon, 21 Sep 2026 00:00:00 GMTUpgrading AWS EKS to AL2023: Troubleshooting Custom Networking and nodeadmhttps://jerrytech.me/en/blog/2026/01/15/Upgrading-AWS-EKS-to-AL2023-Troubleshooting-Custom-Networking-and-nodeadm/https://jerrytech.me/en/blog/2026/01/15/Upgrading-AWS-EKS-to-AL2023-Troubleshooting-Custom-Networking-and-nodeadm/A node startup failure, a config-source mismatch, and the checks that helped us find it.Thu, 15 Jan 2026 00:59:55 GMT