[Thumbgps-devel] Jitter and latency in a linux system might be a problem. Minimal BoM crosspost.

[Eric S. Raymond]

tz <thomas at mich.com>:
> The PPS change detect thread in gpsd might have latency problems if
> the kernel is busy and/or it isn't a high priority - a plain userland
> program shows about 1mS jitter - a loop with the ioctl to block until
> a pin-change followed by gettimeofday will vary over about a 1000 uS
> band on my dual-core netbook.  If you really need 100nS, you might
> need to use the kernel PPS, preferably with a dual core or better CPU
> so the interrupt can capture the nanosecond timer reliably.

We don't need 100ns.  Our target accuracy is 1ms.  This simplifies
things a lot.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>