Linux Memory Setup

On MacOS and Windows memory compression is enabled by default. However on Linux, memory compression (e.g. zram and zswap) is not enabled. Usually this is not an issue, but if you are running a system with limited RAM, enabling these features can help improve performance by compressing memory pages. This document will provide a step-by-step guide to enable zram and zswap on a Linux system.

Zram setup

This quick start guide follows the zram article on the ArchLinux wiki. See the article for more information.

1. Step 1: Install Required Packages

   You can install zram using your package manager. For example, on Debian-based systems, you can run:

   sudo apt install zram-tools
   

2. Step 2: Set up swap area

   To create a swap device for zram, you can use the following command:

   sudo mkswap /dev/zram0
   

3. Step 3: Configure zram settings

   Open /etc/sysctl.d/99-zram.conf with nano:

   sudo nano /etc/sysctl.d/99-zram.conf
   

   Add the following lines to the file:

   vm.swappiness = 180
   vm.watermark_boost_factor = 0
   vm.watermark_scale_factor = 125
   vm.page-cluster = 0
   

   These are the recommended settings according to the ArchLinux Wiki. Feel free to adjust any other zram settings as needed.

4. Step 4: Activate zram

   You can enable zram by running the following command:

   sudo swapon --discard --priority 100 /dev/zram0
   

   It is important that the priority for zram is the highest of all swapfiles. This way, Linux will first use zram and then use other swapfiles.

5. Step 5: Verify zram is active

   To check if zram is enabled and working correctly, you can run:

   swapon
   

   You should see an entry for zram0 in the output, indicating that zram is active.

   Example output:

   NAME       TYPE       SIZE USED PRIO
   /swapfile  file         2G   0B   -2
   /dev/zram0 partition   16G   0B  100
   

   A higher numeric value for priority (PRIO) means that Linux will use the zram0 swap before the swapfile.

6. Step 6: Disabling zram

   If you need to disable zram, you can stop the service and disable it:

   sudo swapoff /dev/zram0
   

Zswap setup

Zswap is usually preinstalled with Debian distributions. To check whether zswap is enabled, run:

cat /sys/module/zswap/parameters/enabled

This will display Y if zswap is enabled and N if it is disabled. The next section shows how to enable zswap and change its parameters for the current session.

To enable zswap, run:

echo 1 | sudo tee /sys/module/zswap/parameters/enabled

Changing zswap parameters is similar to enabling zswap For example, you can change the algorithm by:

echo zstd | sudo tee /sys/module/zswap/parameters/compressor

and the maximum pool percent by:

echo 30 | sudo tee /sys/module/zswap/parameters/max_pool_percent

The max pool percent is the amount of memory zswap is allowed to use for memory compression.