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Date: Wed, 7 Apr 2021 17:40:24 +0300
From: Slawa Olhovchenkov <slw@zxy.spb.ru>
To: Poul-Henning Kamp <phk@phk.freebsd.dk>
Cc: current@freebsd.org
Subject: Re: console getty uses 1.5% of CPU
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On Wed, Apr 07, 2021 at 02:33:57PM +0000, Poul-Henning Kamp wrote:

> > T.e. if all system eat 985 ticks of CPU each second and getty eat 15
> > ticks of CPU each second -- top show 1.5% for getty.
> 
> That may be, but getty should not wake up at all in this situation,
> it should be sleeping, waiting for modem-control signals.


May be some kernel-side ticks counted for getty.
You can try check this by dtrace, I mean.
Snoop scheduler activation and check process accounting.