Multi-Gen LRU is a game changer on my low memory netbook
-
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 levels with high impact to tweak for low RAM/CPU desktop devices. Anything else to tweak under /sys /proc which has impact on performance?
-
System shared this topic on
-
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 levels with high impact to tweak for low RAM/CPU desktop devices. Anything else to tweak under /sys /proc which has impact on performance?
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.
-
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. -
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.
I am running Debian 12 on all of my devices with Debians vanilla kernel!
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.
-
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!
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.
I think I did go with LZ4 after looking at benchmarks; I figured on a weak CPU speed would be more valuable than another few percent of compression. I’ll have to look into the RAM page read-ahead.
-
Debian does not enable it by default, cat /sys/kernel/mm/lru_gen/enabled will be a 0.
I’m on trixie, since recent Mesa has many fixes for very old Radeon GPUs, and it appears to be on by default! At least, I didn’t intentionally turn it on and it’s on.
-
I think I did go with LZ4 after looking at benchmarks; I figured on a weak CPU speed would be more valuable than another few percent of compression. I’ll have to look into the RAM page read-ahead.
Just set vm.page-cluster to 0, to disable the page read-ahead (AFAIK the default value was set when swap was still on rotating disks).
-
I’m on trixie, since recent Mesa has many fixes for very old Radeon GPUs, and it appears to be on by default! At least, I didn’t intentionally turn it on and it’s on.
Does on mean that /sys/kernel/mm/lr_gen/enabled returns 0x7?
-
Does on mean that /sys/kernel/mm/lr_gen/enabled returns 0x7?
Yes indeed.
-
System shared this topic on