[time-nuts] sync computer clock ticks

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Jan 4 22:51:15 EST 2008


Michael Di Domenico wrote:
>> For example, do you want to timestamp interrupts to synchronize
>> machinery? Or just note down the timestamps of bittorrent downloads very
>> precisely? Just synchronizing an otherwise idling computer is probably
>> much easier than a machine that is doing a lot of additional work that
>> can mess up the timekeeping by clogging the processor or just creating
>> varying stress on the power-supply lines.
>>     
>
> The company i work for makes high performance interconnect solutions
> for super computers.  i'm working on a demo where we're sending data
> around a ring and i wanted to timestamp all the packets as it hits
> each node of the ring.  the servers could be under some stress when
> this is running.
>
> i had a feeling what i wanted to do isn't possible, but i figured i'd
> ask some experts before i give up.
>
>   
Unless you use packet time stamping cards as used in network
characterisation.
Errors of around 120ns or so are typical, see:

http://nistboulder.net/Presentations/FCSEFTF2003(final).pdf
<http://nistboulder.net/Presentations/FCSEFTF2003%28final%29.pdf>

Suitable  PCI cards are available.

Bruce


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