Swappiness in Buster
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
Reply to: