console getty uses 1.5% of CPU

Poul-Henning Kamp phk at
Wed Apr 7 05:25:13 UTC 2021

Poul-Henning Kamp writes:
> I have two 12.2-R systems where the serial console is attached to a terminal server.
> When there are no TCP connections to the terminal server, getty soaks up 1.5% of the
> CPU in the kernel (sleeping in "ttyin"), ktrace shows no system calls.
> When a TCP connection is made to the terminal server, which raises the modem-handshake
> on the DE-9 connector, the CPU usage stops.
> Anybody else seeing something like this ?

Just checked, also happens on a similar box running 13.0-ALPHA3

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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