Keep free Oracle Compute instances active with Stress-ng

Oracle Could Infrastructure generously provide completely free compute instances to all users. However, Oracle reserve the right to reclaim idle instances. This article describes how to generate a load capable of satisfying Oracle's definition of activity to prevent reclamation. 

Oracle's definition of Idle

Oracle define idle compute instances as (amongst other things): CPU utilization for the 95th percentile is less than 15% during a 7-day period. 

Generation of a qualifying workload

We can use the utility stress-ng (an extension of stress) to generate a qualifying CPU load of 20% utilisation per core for 75 minutes (or 4,500 seconds) per day. 

Installation and proof

Assuming Oracle Linux 9, Stress-ng is in the ol9_appstream repository therefore can be installed with:

dnf install stress-ng -y

The following snippet generates the necessary workload:

stress-ng -c `grep -c ^processor /proc/cpuinfo` -t 4500 -l 20

where:

-c `grep -c ^processor /proc/cpuinfo`

gets the CPU count, to ensure each CPU will be stressed, and,

-t 4500

times the job for 4,500 seconds (One hour and 15 minutes), and,

-l 20

limits the CPU loading to 20%.

In the Oracle Cloud Infrastructure Compute Instance Detail page for the VM in question, we can observe CPU usage Metrics to confirm the load we generated: 

Schedule the loading

To run the load regularly without intervention, sudo su - to the root user, then crontab -e to access the root cron table. Append the following line to run the job at 04:30 each morning (adjust as per your own requirement):

30 04 * * * stress-ng -c `grep -c ^processor /proc/cpuinfo` -t 4500 -l 20