On my low RAM/CPU netbook it is a game changer; thanks to ZRAM the netbook is perfect for browsing the internet/light work. When running my backups (creates big tarballs) or Ansible though, my desktop/applications would freeze/stutter noticeably. Enabling MGLRU simply solved the problem of freezes/stuttering, it feels like magic and besides ZRAM, I don’t know of any other lever with this massive impact on desktop performance.
Just wanted to share this, for other users with low RAM/CPU hardware. I would assume the observed difference is less dramatic, once 8GB of RAM are available, but I would love to hear about other experiences.
I would also love to hear/learn about other levers with high impact to tweak for low RAM/CPU desktop devices. Anything else to tweak under /sys /proc which has impact on performance?
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Did you need to compile a kernel to enable it? I’ve just done the project of installing Debian on a 20 year old iMac with 2.5 GB of RAM, and while zram definitely seems to help, I’d love to try this as well.
Yes, but maybe debian enables it by default? You can check by running
cat /sys/kernel/mm/lru_gen/enabledIf the result is
0x0007, it means MGLRU is fully enabled.Debian does not enable it by default, cat /sys/kernel/mm/lru_gen/enabled will be a 0.
I am running Debian 12 on all of my devices with Debians vanilla kernel! :-) Just enable MGLRU on Debian like it is described in this blogpost.
One further tip for ZRAM: On my device the LZ4 algorithm was noticeable faster than ZSTD (didn’t try ZSTD with the enabled MGLRU, yet) and it was important to disable the RAM page read-ahead on my device.