Insufficient CPU limits cause sidecar throttling

Conservative CPU limits on the istio-proxy container can cause CPU throttling, degrading sidecar performance and increasing request latency. Throttling occurs when the container exceeds its CPU quota, forcing the kernel to restrict CPU time.

Set sidecar CPU requests and limits using sidecar.istio.io/proxyCPU and sidecar.istio.io/proxyCPULimit annotations (e.g., 50m request, 200m limit). Check for throttling using: kubectl exec -it deploy/my-app -c istio-proxy -- cat /sys/fs/cgroup/cpu/cpu.stat. Look for increasing nr_throttled and throttled_time values. Increase limits if throttling detected.