More RAM Without Adding RAM? How to Configure ZRAM on TUXEDO OS - TUXEDO Computers

Given the high cost of memory and the tense market situation, many buyers of new computers consider cutting back on RAM. For numerous tasks, a smaller configuration may seem sufficient at first. In everyday use, however, bottlenecks can appear quickly. When physical RAM becomes scarce, Linux moves data to the significantly slower swap area on the SSD or hard drive — noticeable through stuttering applications, delayed responses, and an overall less responsive desktop.

This is where ZRAM comes into play: the technology built into the Linux kernel creates a compressed block device directly in memory that acts as additional swap space. Instead of writing data immediately to the slower drive, it is first compressed and stored in RAM. As a result, more information remains in fast main memory, and the system accesses the disk less frequently. The trade-off is a slightly higher CPU load due to compression — typically negligible in practice.

Initial situation: Installation with swap space

For illustration, let us look at a productively used notebook running TUXEDO OS. The system is equipped with 32 GB of RAM and an equally sized 32 GB swap file located at /swapfile in the root directory. This is explicitly not a fresh installation: several services and everyday applications are already running in the background. Immediately after booting into the Plasma desktop, the system therefore occupies around 7 GB of RAM, while the swap area remains unused at first.

You can check the current status on your system using free -m or swapon -s, or graphically via the System Monitor in KDE Plasma.

free -m
(out)               total        used        free      shared  buff/cache   available
(out)Mem:           31834        7112       22974         291        2440       24721
(out)Swap:          32767           0       32767

swapon -s
(out)Filename				Type		Size		Used		Priority
(out)/swapfile                               file		33554428	0		-2

Installing ZRAM and checking its current status

On TUXEDO OS — just as on Ubuntu — you can conveniently enable ZRAM via the zram-config package. Install it using the following command. A reboot is usually required afterward; no manual basic configuration is necessary, as the system sets up ZRAM automatically.

sudo apt install zram-config

After rebooting, use zramctl to verify that the system has created the ZRAM device correctly. By default, the preset reserves about half of the available RAM for ZRAM. On a machine with 32 GB of RAM, you will therefore see an additional ZRAM device of roughly 16 GB alongside the classic swap area. The free -m tool combines ZRAM and traditional swap into a single swap total.

swapon -s
(out)Filename				Type		Size		Used		Priority
(out)/swapfile                               file		33554428	0		-2
(out)/dev/zram0                              partition	16299324	0		5

zramctl
(out)NAME       ALGORITHM DISKSIZE DATA COMPR TOTAL STREAMS MOUNTPOINT
(out)/dev/zram0 lzo-rle      15,5G   4K   74B   12K      20 SWAP

free -m
(out)               total        used        free      shared  buff/cache   available
(out)Mem:           31834        6522       23989         128        1845       25312
(out)Swap:          48685           0       48685

When is it worth adjusting the ZRAM size?

The optimal size depends heavily on your usage scenario. The key factors are how well your typical data can be compressed and how severely your system suffers from memory pressure.

• Multimedia and video editing: Audio and video data are often already compressed. Additional compression by ZRAM provides limited benefit here. In such cases, it may make sense to allocate less memory to ZRAM and instead enlarge the traditional swap area.
• Databases or highly compressible data: Text-heavy or structured data often benefits significantly from compression. A larger ZRAM partition can noticeably improve system responsiveness.

Adjusting the ZRAM size

The size of ZRAM is defined via the init-zram-swapping script located in /usr/bin/:

#!/bin/sh
modprobe zram

# Calculate memory to use for zram (1/2 of ram)
totalmem=LC_ALL=C free | grep -e "^Mem:" | sed -e 's/^Mem: *//' -e 's/  *.*//'
mem=$((totalmem / 2 * 1024))

# initialize the devices
echo $mem > /sys/block/zram0/disksize
mkswap /dev/zram0
swapon -p 5 /dev/zram0

Open the file with administrative privileges in a text editor of your choice:

sudo nano /usr/bin/init-zram-swapping

Locate the line starting with mem=. By default, it reserves half of the available RAM. If you want to adjust the size, modify the multiplication factor accordingly:

• Reduce: For example, replacing 1024 with 512 limits ZRAM to one quarter of the total RAM.
• Increase: Setting the factor to 1536 allocates roughly three quarters of the RAM to ZRAM.

Save the file and reboot the system for the changes to take effect.

Changing the ZRAM compression algorithm

By default, ZRAM typically uses LZO or LZO-RLE. These algorithms require little CPU power and therefore represent a good compromise. Modern processors, however, often handle ZSTD without difficulty, offering a higher compression ratio and thus potentially more effective memory gain.

First, check which algorithms are available:

cat /sys/block/zram0/comp_algorithm
(out)lzo-rle lzo lz4 lz4hc zstd deflate 842 

Then modify the init-zram-swapping script. Locate the following line:

…
echo $mem > /sys/block/zram0/disksize
…

Insert a new line directly above it to define the desired algorithm:

…
echo zstd > /sys/block/zram0/comp_algorithm
echo $mem > /sys/block/zram0/disksize
…

Save the file and reboot the system. Finally, use zramctl to verify that the new compression algorithm is active.