An ontology of clocks

Hal Murray hmurray at
Mon Feb 22 11:25:40 UTC 2016

kurt at said:
> I'm sure what you mean by corrupt in the case of suspending.  It's still
> measuring something, but maybe not something you (or ntp) cares about.  I
> guess this falls under your category of "clocks that count time
> selectively". 

Some clocks get turned off when suspended to save power.  Details vary.  It 
takes time to get the crystal started so you may not want to turn it off 
between keystrokes.

kurt at said:
> There is also at least /dev/hpet that you might want to look at. 

Most of that sort of clock are all derived from the main CPU crystal which 
generates several clocks via PLLs.

For the detail collection...

The CPU clock and friends are probably smeared slightly to dance around the 
FCC's EMI rules.  That means wiggling the frequency slightly.  I think the 
wiggle is typically in the ballpark of 50kHz.  It's slow enough so that PLLs 
can track it and fast enough to keep the FCC happy.

These are my opinions.  I hate spam.

More information about the devel mailing list