Part 4: System Optimization

/proc file systems

The /proc and /sys sudo file systems, and how these file systems are used by the Linux kernel to keep current status information.

• Performance analyzing tools mine the contents of the proc file system.
• Every process has a file in the PID directory

/proc/sys

fs

kernel

net

vm

Notes on sysctl

sysctl settings are defined through files in

/usr/lib/sysctl.d/
/run/sysctl.d/
/etc/sysctl.d/ <– Custom config

Vendors settings  in /usr/lib/sysctl.d/.

sysctl -a Output of tunable.

sysctl -w <setting> Run time setting change

sysctl -p Reloads configuration files

To override a whole file, create a new file with the same in
/etc/sysctl.d/ and put new settings there. Edit /etc/sysctl.conf to load custom settings too.

To override specific settings, add a file with a lexically later name in /etc/sysctl.d/ and put new settings there.

For more information, see sysctl.conf(5) and sysctl.d(5).

Change values on the command-line before making persistent.

Example: (reduce swappiness)

cd /proc/sys/vm

echo 10 > swappiness