Hello, ever since upgrading machines to Buster the vm.swappiness sysctl parameter doesn't seem to do anything anymore and regardless on how I set it via sysctl or directly in /proc the system behaves as it would have a pretty high swappiness and thus is swapping out quite a bit under load, using the memory mostly for buff/cache.
To make this clear, I'm seeing no performance degradation and there is not much swapping in done, I'm merely wondering why this behaviour has changed and if there's a way to make it work as before again. Also I'd be happy to know if anybody else is experiencing this as Buster has been out for a while now and I found some information on this ie. other users reporting the same issue, but not really a lot. Now if you're asking why I would configure swap if I don't want it to be used, the answer is monitoring and failsafe. I usually set the swappiness to 1 so to only swap if the box runs out of memory and then trigger an alarm to let us know something is up. This is much more convenient than the oomkiller striking down a mysqld process just because it was allowed to use a bit too much memory. Cheers, Martin