ntpd: Gross CPU usage

[Eric S. Raymond]

Hal Murray <hmurray at megapathdsl.net>:
> 
> devel at ntpsec.org said:
> > First thing to suspect on seeing that symptom, in ntpd or gpsd, is that
> > somebody's tty layer is reacting badly to the unusual ways we use ioctls.
> > I've seen this before multiple times. 
> 
> Thanks.  That's the hint I needed.
 
One of the more unfortunate things I learned from working on GPSD is that
kernel serial layers are often wretched hives of scum and villainy.  This is
true across several different OSes I've had to work with, so it's not
just some Linux flakiness.

They tend to be good at handling the common cases but to get weird when
pushed into rarely-visited portions of their behavior space.  Danger areas
definitely include strange combinations of mode bits and ioctl calls.

The consequences can be nasty.  You may not have been paying enough attention
to notice, a few years back when some kind of screaming-TTY bug in a Samsung
port of Android interacted badly with gpsd.  The result was rapid battery
drainage for the users. 
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>

My work is funded by the Internet Civil Engineering Institute: https://icei.org
Please visit their site and donate: the civilization you save might be your own.