OpenBSD 6.5 is much less responsive (high "spin" state)
Recently I upgraded an OpenBSD amd64 server from 6.3 to 6.5 (rapidly
passing through 6.4). This a monitoring server with a lot of processes
that send "ping" (both ICMP and UDP) packets to a great number of hosts.
So there is a great number of processes but they spend most of their
time waiting (for packets to return).
Since the upgrade to 6.5 I have seen a GREAT increase in ping delays and
variance. It seems that the system is much less "real-time" (yes, I know
that OpenBSD is not a REAL real-time system).
I noticed that, when many processes are running, a lot of time is spent
in "spin" state (even more than 50%).