In this hands-on lab, you will focus on managing system resource limits using `control groups` (`cgroups`). Using `top` or a similar tool, you will review CPU activity and identify the `PID` of a high CPU process, then create a control group and set a limit using the `PID` value and confirm the limits were properly applied. The final task will be to start a service, monitor the CPU utilization, and create a permanent resource limit using a `systemd` control file for the service.
*This course is not approved or sponsored by Red Hat.*
Learning Objectives
Successfully complete this lab by achieving the following learning objectives:
- Use cgroups to Manage Settings at the PID Level
- Launch the
cg-review.shscript as a background application. - Launch your preferred utility to monitor processes and monitor CPU and memory utilization, such as
top.- Identify any processes that are consuming excess CPU and note the
PIDvalue.
- Identify any processes that are consuming excess CPU and note the
- Configure the limit values:
- Create a directory called
labin/sys/fs/cgroup/cpu/.- Confirm the directory is populated.
- As the
rootuser, set the limits as follows:cpu.cfs_period_us= 1000000cpu.cfs_quota_us= 200000- Confirm the values are configured.
- Add the process PID to the
cpu/lab/cgroup.procsfile for thelabcgroup.- Confirm the limit was applied by checking in
/proc.
- Confirm the limit was applied by checking in
- Launch
topand check for the process, confirming the CPU usage has been limited as expected.
- Create a directory called
- Kill the process.
- Exit the root account
- Launch the
- Manage Resource Limits Using systemd
- Enable and start the
evotlservice.Note: This service will cause the
systemd-journaldservice to consume around 50% of the CPU at times. This is ok for the purposes of the lab.- This service spawns a
tailprocess that consumes around 2G of memory.
- This service spawns a
- Check the status of the
evotlservice. - Launch
topand review the top memory processes.- You should see the
tailprocess consuming approximately 50-55% of the memory.
- You should see the
- Use
systemctlto set theMemoryLimitproperty to 1000M.Note: This could take a several seconds to complete, be patient.
- Check the status of the change.
- Use
systemctlto view theevotlservice and confirm a limit file was created. - Launch
topand confirm thetailprocess now consumes around 25% of the memory.
- Use
- Enable and start the
- Reboot the Lab and Confirm Configuration Persists
- Use
systemctlto check the status of theevotlservice.- Confirm the service still has the memory limit in place.
- Launch
topand monitor the status of the tail process.- Confirm the process is currently consuming around 25% of the memory.
- Use
- Revert the Memory Limit and Disable the Service
- Stop the
evotlservice. - Remove the
50-MemoryLimit.conffile for theevotlservice. - Disable the
evotlservice.
- Stop the
