[CentOS] CentOS 7, systemd,, and message floods

I've just updated a couple of servers, latest 7.3, and systemd is flooding
dmesg, journalctl with info level messages... or maybe debug level 1.

Examples:
[  478.258571] systemd[1]: Sent message type=signal sender=n/a
destination=n/a object=/org/freedesktop/systemd1/unit/httpd_2eservice
interface=org.freedesktop.DBus.Properties member=PropertiesChanged
cookie=436 reply_cookie=0 error=n/a

[  478.258971] systemd[1]: Got notification message for unit
systemd-logind.service
[  478.258980] systemd[1]: systemd-logind.service: Got notification
message from PID 821 (WATCHDOG=1)
[  478.258985] systemd[1]: systemd-logind.service: got WATCHDOG=1

What *is* all that garbage, and is there some way to turn it down to WARN
and ERR messages?

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