Re: [OT] Friday the 13th
On 2009-02-10_10:20:03, John Hasler wrote:
> Mark Allums writes:
> > Totally irrelevant, but: Isn't the Linux epoch 64 bits?
>
> Only with a 64 bit kernel.
> --
> John Hasler
I think you are mistaken. The current _standard_ is 64 bits for unix
time. Most actual computers don't yet carry the extra 32 high order
bits, and do their calculations assuming that they are all zero. It
will be no problem to implement a 64 bit counter on a 32 bit computer
well before it is needed. It may already be implemented in linux. And
when the computer clock is set to the correct time that extra 32 bit
word is all zeros.
On 64 bit computers, most kernels didn't implement the extra code to
use only a half word when the _standard_ was 32 bits.
OT: The standard also does not recognize leap seconds. How does that
work? A computer that has a really stable clock ticking once per
second, would suddenly be one second fast when a leap second is
'added'. And as more leap seconds are added over time, the computer
clock would become several seconds off from 'true' UTC. Isn't this a
problem? No. Nobody runs a computer connected to the internet without
connecting to an NTP server regularly. These servers simply change
what they say is the unix time at the moment when a leap second is
officially declared to happen. All us users just see our computers
being one second off from what the NTP server says, and change our
clocks.
--
Paul E Condon
pecondon@mesanetworks.net
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