Tutorial 29-31

Q1 Process Cleanup & User Process Management

A user named anil exists on the system and has left rogue processes running in the background. Additionally, a hung task is leaving orphaned resources on the system.

Task

Identify all running processes owned by user anil and terminate them cleanly without deleting the user account.
Ensure no processes associated with the executable name sleep remain active for user anil.
Locate any defunct (zombie) processes running on the system.
Identify the Parent Process ID (PPID) of the zombie process and terminate the parent process so the zombie is fully reaped.

Solution

User Creation & Run Background Process

Create user
- sudo useradd anil
Change password
- sudo passwd anil
Switch user
- su - anil
Run dummy background process
- sleep 600 &
Logout
- exit

Gently Kill User Process

Find processes owned by a specific user
- ps -u anil
Terminate all processes
- pkill -u anil
- pkill -9 -u anil sleep (Force if needed)
Verify
- ps -u anil

Zombie Process

Monitor "zombie" processes
- ps aux | grep defunct
Find the zombie process parent PID
- ps -o ppid= -p [Zombie process PID]
- Example: ps -o ppid= -p 4745
Kill the zombie parent process
- kill -SIGTERM [Zombie parent process PID]
- Example: kill -SIGTERM 4743
Verify
- ps aux | grep defunct

Cleanup

Delete user
- sudo userdel -r anil

Q2 Persistent Kernel Parameter Tuning

Your system's database performance requirements dictate a lower memory swappiness value to prefer keeping process pages in RAM rather than moving them to swap.

Task

Configure the system kernel parameter for swappiness (vm.swappiness) to a value of 40.
This configuration must persist across system reboots.
Do not modify system defaults in /etc/sysctl.conf directly; create a custom configuration file named /etc/sysctl.d/10-swappiness.conf.
Load the new configuration immediately without rebooting the server.

Solution

Direct to sysctl.d
- cd /etc/sysctl.d/
Create new configuration file in /etc/sysctl.d/
- echo "vm.swappiness=40" | sudo tee -a /etc/sysctl.d/10-swappiness.conf
Verify configuration
- cat -b 10-swappiness.conf
Apply configuration
- sudo sysctl --system
Verify
- sysctl vm.swappiness
Cleanup
- sudo rm /etc/sysctl.d/10-swappiness.conf
- sudo sysctl --system

Q3 Dynamic Tuning with Tuned Daemon

The server is scheduled to run inside a virtualized hypervisor environment, and performance needs to be optimized for guest virtual machine workloads.

Task

Query the tuning daemon (tuned) to identify the recommended performance profile for this system.
Set the active tuned profile to virtual-guest.
Verify that the profile is active and operational.

Solution

Check status of systemctl
- systemctl status tuned
- If tuned service not enabled, enabled and start the service : sudo systemctl enable --now tuned
Ask system to recommend a profile
- tuned-adm recommend
Change profile
- tuned-adm profile virtual-guest
Verify
- tuned-adm active

Q4 Custom Profile Deployment & Process Scheduling

A specialized application suite requires custom kernel tuning along with constrained CPU execution parameters for intensive background tasks.

Task

Create a custom tuned profile named myprofile located in /etc/tuned/profiles/myprofile/.
Configure tuned.conf within this profile to set vm.swappiness = 66 under the [sysctl] directive.
Activate the new profile using tuned-adm and verify that vm.swappiness reflects 66.
Launch a background task copying /dev/zero to /dev/null strictly bound to CPU core 0 with a custom nice value of 10.

Solution

Create new profile directory
- mkdir /etc/tuned/profiles/myprofile
Create new configuration file
- sudo tee -a /etc/tuned/profiles/myprofile/tuned.conf <<STOP
- [sysctl]
- vm.swappiness = 66
- STOP
Change profile
- tuned-adm profile myprofile
Verify active profile
- tuned-adm active
Verify swappiness after change profile
- sysctl vm.swappiness
Background task
- taskset -c 0 nice -n 10 dd if=/dev/zero of=/dev/null &
Verify
- ps -o pid,psr,ni,cmd -p [PID]
- Example: ps -o pid,psr,ni,cmd -p 4177
Cleanup
- jobs ---> fg %[Job Index] ---> Ctrl+C
- tuned-adm profile balanced
- rm -rf /etc/tuned/profiles/myprofile

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