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@coolo do you think we should still try to tinker with these variables? I don't think the mentioned problems are relevant anymore but of course we can still try improve based on vm options.

What makes you think linux's memory management got any better since?

It had - I'm going to increase it to 10%/5% again. This is still 50% of the default, but way above the current settings

I asked the DLs for 5 SSDs, let's see :)

You did https://gitlab.suse.de/openqa/salt-states-openqa/merge_requests/215 and called it "Increase the dirty buffer size" whoever I believe you are actually decreasing it as the values are lower than default.

I have good experience with the following:

# https://askubuntu.com/questions/157793/why-is-swap-being-used-even-though-i-have-plenty-of-free-ram
# https://askubuntu.com/questions/440326/how-can-i-turn-off-swap-permanently
# https://superuser.com/questions/1115983/prevent-system-freeze-unresponsiveness-due-to-swapping-run-away-memory-usage
vm.dirty_background_ratio = 5
vm.dirty_ratio = 80
# okurz: 2019-01-04: Trying to prevent even more stuttering
# vm.swappiness = 10
# https://rudd-o.com/linux-and-free-software/tales-from-responsivenessland-why-linux-feels-slow-and-how-to-fix-that
vm.swappiness = 1
# did not actually experiment with finding a good value, just took the one from the above webpage
vm.vfs_cache_pressure = 50

As an alternative we can say whenever we hit problems due to this we need to simply buy more RAM.

WDYT?

you don't understand the problem I'm afraid. this has nothing to do with RAM nor with swap.

ok maybe I was misleading with mentioning the part about swap or thrashing. It's not about memory depletion for sure. So let me simply ask: Did you not decrease the values below default now?

the default is 10% of memory which is about 26GB - our initial hit was at 200MB (which is less than 1% of default), which was too small. Now we're at 5% of memory, which is somewhere in the middle