Trouble Shooting

Kepler Pod failed to start

Background

Kepler uses eBPF to obtain performance counter readings and processes stats. Since eBPF requires kernel headers, Kepler will fail to start up when the kernel headers are missing.

Diagnose

To confirm, check the Kepler Pod logs with the following command and look for message not able to load eBPF modules.

kubectl logs -n kepler daemonset/kepler-exporter

Solution

Installing kernel headers on each node can be done manually using the following command

# Fedora/RHEL based distro
dnf install kernel-devel-`uname -r` -y
# Debian/Ubuntu distro
apt install linux-headers-$(uname -r)

On OpenShift, install the MachineConfiguration here

Kepler energy metrics are zeroes

Background

Kepler uses RAPL counters on x86 platforms to read energy consumption. VMs do not have RAPL counters and thus Kepler estimates energy consumption based on the pre-trained ML models. The models use either hardware performance counters or cGroup stats to estimate energy consumed by processes. Currently the cGroup based models use cGroup v2 features such as cgroupfs_cpu_usage_us, cgroupfs_memory_usage_bytes, cgroupfs_system_cpu_usage_us, cgroupfs_user_cpu_usage_us, bytes_read, and bytes_writes.

Diagnose

The Kepler metrics are zeroes, check if cGroup version on the node:

ls /sys/fs/cgroup/cgroup.controllers

Solution

Enable cGroup v2 on the node by following these Kubernetes instruction.