zswap-unit.md

How to use zswap with a systemd unit

1. Create a systemd unit:
   sudo nano /etc/systemd/system/zswap.service

2. Add the following lines:

[Unit]
Description=Zswap Memory Compression

[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/bin/sh -c "\
 modprobe z3fold;\
 echo Y > /sys/module/zswap/parameters/same_filled_pages_enabled;\
 echo 25 > /sys/module/zswap/parameters/max_pool_percent;\
 echo zstd > /sys/module/zswap/parameters/compressor;\
 echo zsmalloc > /sys/module/zswap/parameters/zpool;\
 echo z3fold > /sys/module/zswap/parameters/zpool;\
 echo Y > /sys/module/zswap/parameters/enabled;\
 echo 25 > /proc/sys/vm/swappiness"
ExecStop=/bin/sh -c "\
 echo 25 > /proc/sys/vm/swappiness;\
 echo N > /sys/module/zswap/parameters/enabled"

[Install]
WantedBy=multi-user.target

3. Enable the systemd unit:
   sudo systemctl enable zswap.service

4. Start the systemd unit:
   sudo systemctl start zswap.service

5. See log files for the unit:
   sudo journalctl -f zswap

6. See status of unit:
   sudo systemctl status zswap.service

7. To see the zswap parameters at runtime:
   grep -R . /sys/module/zswap/parameters

8. If you modify the unit's content, disable and enable it to apply the changes.