[time-nuts] sync computer clock ticks

David I. Emery die at dieconsulting.com
Thu Jan 3 22:24:33 EST 2008

On Thu, Jan 03, 2008 at 10:14:01PM -0500, Michael Di Domenico wrote:
> I'd like to synchronize the clock ticks on 16 different computers
> running linux, down to the 1usec area.  Is this even possible from a
> computer hardware standpoint?
> Ideally, I'd like to use the serial port on each of these 16 servers
> to connect to some device to get the synchronization signal from a
> reference.  Even if this was possible, i don't think it would get me
> to 1usec though.

	I've had ntp sync of the microsecond/nanosecond time of day
counter on Linux in the 1 us area using serial port timing with custom
mods to the kernel (years ago, I think this is standard now)...

	This of course DOES NOT sync the actual clock tick interrupts,
it only syncs the microclock stuff...

	The only way I know to sync clock interrupts is to use a common
clock oscillator and even then the actual interrupt times will not be
synced... unless one does some hardware modifications to the motherboards

	But it certainly IS possible to get multiple machines to see the
same time of day to with around a microsecond or two...

  Dave Emery N1PRE/AE, die at dieconsulting.com  DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in 
celebration of what could have been, but wasn't and is not to be now either."

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