Optimal settings for Swap, ZSwap etc.?

[juliaaa]

Hey,

does anyone know what would be good values for the following Swap, ZSwap etc. settings:


# in /etc/sysctl.conf:

vm.swappiness=20
vm.vfs_cache_pressure=100
vm.dirty_ratio = ??
vm.dirty_background_ratio = ??


# in /etc/default/grub:

zswap.enabled=1
zswap.compressor=lz4
zswap.max_pool_percent=30
zswap.same_filled_pages_enabled=1
zswap.zpool=z3fold


Also, are there any other interesting parameters to tweak?

I've read about 20 articles/tutorials, but I'm still not really sure about the decision-making regarding many of these settings. And there are conflicting statements, too, for example regarding values for vfs_cache_pressure and max_pool_percent or zsfold vs. zmsalloc for compression.

I'm currently running LMDE4 on an old R60 9461-DXG upgraded with a T7400, 4 GB RAM and an SSD. The machine is used mostly for office work, image processing using GIMP and, of course, web browsing using Firefox (which is a terrible resource hogger). Someone recommended using the h264ify addon with which I can now run 720p (not 720p60) YouTube videos and even 1080p with only sporadic hiccups.

Is it possible to make intelligent guesses for these settings according to the hardware specs or do I have to run measurements?

PS.: What I noticed with certain settings is that the left side of the handrest is getting warmer (probably the CPU/GPU). Does this observation make sense, i.e. can some of these settings have significant impact on heat generation?

[RealBlackStuff]

Be courageous, replace Firefox with Brave: https://brave.com/linux/

[juliaaa]

Hey, thanks for the suggestion. Actually, I used to use Brave for a while on Android, but I heard it's collecting personal information in order to feed their own ad network or something. Also, there was some usability issue which is why I dumped it (although that was 2 years ago)...haven't really tried alternative browsers since except the TOR browser bundle. What speaks for the current Brave version?

[axur-delmeria]

Enabling ZSwap adds some CPU load (compressing and decompressing data), though I don't know by how much.

If you want to reduce the temps, then you can try undervolting the CPU.

[davidgurvich]

Not sure I'd be using ZFS on a laptop. There's no gain for single drive and some overhead. Not surprising that system is running hotter. I think most of the tuning can be left to defaults until you need to do something specific.

[axur-delmeria]

Not sure I'd be using ZFS on a laptop. There's no gain for single drive and some overhead. Not surprising that system is running hotter. I think most of the tuning can be left to defaults until you need to do something specific.

I think you've gotten confused
It's not the filesystem ZFS, but the in-memory compressed swap cache Zswap. It's useful for systems with low RAM.

[natumbri]

Have you checked out these projects:

https://github.com/ecdye/zram-config
https://github.com/StuartIanNaylor/zram-swap-config

Quite a bit of useful thinking about zram and how to use it. I use it (with Ubuntu Mate) on all my gear.

Cheers
Nik

[Dekks]

Hey,

does anyone know what would be good values for the following Swap, ZSwap etc. settings:


# in /etc/sysctl.conf:

vm.swappiness=20
vm.vfs_cache_pressure=100
vm.dirty_ratio = ??
vm.dirty_background_ratio = ??


# in /etc/default/grub:

zswap.enabled=1
zswap.compressor=lz4
zswap.max_pool_percent=30
zswap.same_filled_pages_enabled=1
zswap.zpool=z3fold


Also, are there any other interesting parameters to tweak?

I've read about 20 articles/tutorials, but I'm still not really sure about the decision-making regarding many of these settings. And there are conflicting statements, too, for example regarding values for vfs_cache_pressure and max_pool_percent or zsfold vs. zmsalloc for compression.

I'm currently running LMDE4 on an old R60 9461-DXG upgraded with a T7400, 4 GB RAM and an SSD. The machine is used mostly for office work, image processing using GIMP and, of course, web browsing using Firefox (which is a terrible resource hogger). Someone recommended using the h264ify addon with which I can now run 720p (not 720p60) YouTube videos and even 1080p with only sporadic hiccups.

Is it possible to make intelligent guesses for these settings according to the hardware specs or do I have to run measurements?

PS.: What I noticed with certain settings is that the left side of the handrest is getting warmer (probably the CPU/GPU). Does this observation make sense, i.e. can some of these settings have significant impact on heat generation?

wrt Zswap you can remove the same_pages_filled line as your only stating the default, it's only use if is you want to switch it off, you could also try lzo as compressor.

to view zswap performance run "sudo grep -R . /sys/kernel/debug/zswap/" or create a bash alias for it to view the zswap cache performance. 30% pool size might be fine for 4G RAM but 2G RAM configs might want to look ar 25%.