Re: PSA: Clock drift and pkgin

Mouse <[email protected]>
Newsgroups gmane.os.netbsd.devel.kernel
Message-ID <[email protected]>
> Better than 100Hz is possible and still precise.  Something around
> 1000Hz is necessary for human interaction.

That doesn't sound right.  I've had good HCI experiences with HZ=100.
Why do you see a higher HZ as necessary for human interaction?

> Modern hardware could easily do 100kHz.

Not with curren^Wat least one moderately recent NetBSD version!

At work, I had occasion to run 9.1/amd64 with HZ=8000.  This was to get
8-bit data pushed out a parallel port at 8kHz; I added special-case
hooks between the relevant driver and the clock (I forget whether
softclock or hardclock).  It worked for its intended use fairly
nicely...but when I tried one of my SIGALRM testers on it, instead of
the 100Hz it asked for, I got signals at, IIRC, about 77Hz.

I never investigated.  I think I still have access to the work machine
in question if anyone wants me to try any other quick tests, but trying
to figure out an issue on a version I don't use except at work is
something I am unmotivated to do on my own time, and using work time to
dig after an issue that doesn't affect work's use case isn't an
appropriate use of work resources.

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