Advanced RAM use on all Bash installed systems

Advanced Free memory

Bash script that you can use in a cron job to clean the RAM if it's more than 90% used:

#!/bin/bash

# Set the threshold for free memory in bytes
THRESHOLD=$(( 90 * $(grep MemTotal /proc/meminfo | awk '{print $2}') / 100 ))

# Get the current amount of free memory
FREE=$(grep MemAvailable /proc/meminfo | awk '{print $2}')

# Check if free memory is below the threshold
if [ $FREE -lt $THRESHOLD ]; then
  echo "Cleaning RAM..."
  
  # Clear pagecache, dentries and inodes
  sync && echo 3 > /proc/sys/vm/drop_caches
  
  echo "RAM cleaned."
else
  echo "No need to clean RAM."
fi

How the script works:

• The THRESHOLD variable is set to 90% of the total amount of RAM on the system, in bytes.
• The FREE variable is set to the current amount of free memory on the system, in bytes.
• If the amount of free memory is less than the threshold, the script clears the page cache, dentries, and inodes using the sync and drop_caches commands.
• The script outputs a message indicating whether or not RAM cleaning was performed.

You can save this script to a file (e.g. clean_ram.sh) and make it executable using the command

chmod +x clean_ram.sh

Then, you can add it to a cron job to run at regular intervals, like this:

# Run the script every 5 minutes
*/5 * * * * /path/to/clean_ram.sh

This will run the script every 5 minutes and check if the amount of free memory is below the threshold. If it is, the script will clear the RAM cache to free up memory. This script should work on all of the Linux and BSD systems.

Advanced ZRAM use

Zram is a Linux kernel module that allows for compressed RAM-based swap space. Using Zram can improve performance on systems with limited RAM, as it can reduce the amount of data that needs to be written to disk.

Check if Zram is already installed.

Run the following command to check if the zram module is already installed:

lsmod | grep zram

If the output shows the zram module, then it's already installed. If not, you can install it using the appropriate package manager for your distribution.

Create a Zram device.

Once Zram is installed, you can create a Zram device using the following command:

sudo modprobe zram num_devices=1

This will create one Zram device with default parameters. You can specify a different number of devices or customize other parameters as needed.

Configure the Zram device. After the Zram device is created, you need to configure it by setting the size of the swap space and enabling compression. Here's an example configuration that sets the size of the swap space to 1 GB and enables compression:

sudo sysctl -w vm.swappiness=10
sudo zramctl -f -s 1g -t 2

This sets the vm.swappiness value to 10 (which determines how aggressively the kernel swaps out memory to disk), creates a Zram device with a 1 GB swap size, and enables LZ4 compression with a compression ratio of 2:1.

Mount the Zram device. Finally, you need to mount the Zram device as swap space using the following command:

sudo mkswap /dev/zram0
sudo swapon /dev/zram0

This formats the Zram device as swap space and activates it. You can check if the Zram device is being used as swap space by running the following command:

sudo swapon -s

This will show a list of all the active swap devices, including the Zram device if it's being used. -- You can automate this process by adding the necessary commands to a Bash script and running it as a cron job or a systemd service --

Zram swap space as a percentage of the physical RAM

You can configure the size of the Zram swap space as a percentage of the physical RAM by using the total_mem option when creating the Zram device. In this example we create a Zram device with a swap space size of 25% of the physical RAM:

sudo zramctl --find --size $(($(free | awk '/^Mem:/{print $2}') / 4)) --mkswap

This command uses the free command to get the total amount of physical RAM, divides it by 4 to get 25%, and sets the size option of the zramctl command to the calculated value. The --find option tells zramctl to find an unused device number, and the --mkswap option tells it to format the device as swap space.

Once the Zram device is created, you can activate it as swap space using the swapon command:

sudo swapon /dev/zram0

This will activate the Zram device as swap space, and it will be used by the system when the physical RAM is running low. You can check if the Zram device is being used as swap space by running the swapon -s command.

Note that while Zram can improve performance by reducing the amount of data that needs to be written to disk, it is not a substitute for physical RAM. If you're running memory-intensive applications, it's still recommended to have enough physical RAM to avoid excessive swapping.

This Bash scripts should work on any Linux system that has Bash installed, as well as other Unix-like systems that have Bash installed.

Other tips and tricks to optimize and clean up your RAM on Bash-installed systems:

Use a lightweight window manager or desktop environment.

Using a lightweight window manager or desktop environment can reduce the amount of memory used by the system, leaving more free memory available for applications. Some popular lightweight options include Xfce, LXDE, and Openbox.

Disable unnecessary services and daemons.

Disabling unnecessary services and daemons can free up memory and reduce CPU usage. Use the systemctl command to manage systemd services, and use the chkconfig command to manage SysV init services.

Close unused applications and tabs.

Closing unused applications and tabs can free up memory and reduce the load on the CPU. Use a task manager such as htop or top to monitor system resources and identify any applications or processes that are using excessive resources.

Use the nice command to prioritize processes.

The nice command can be used to adjust the priority of a process, giving it more or less CPU time. Prioritizing CPU-intensive processes can help reduce the load on the CPU and free up more memory.

Clear the disk cache.

• Clearing the disk cache can free up memory and improve system performance. Use the sync command to write data to disk, and then use the

sudo echo 3 > /proc/sys/vm/drop_caches 

command to clear the page cache, dentries, and inodes.

Use the ulimit command to set process limits.

• The ulimit command can be used to set limits on system resources such as CPU time and memory usage for individual processes. This can help prevent processes from using excessive resources and causing the system to become unresponsive. These tips and tricks can help optimize and clean up your RAM on Bash-installed systems, improving system performance and reducing the likelihood of crashes and freezes due to insufficient memory.

copyright Volkan Sah