On 6 Aug 99, at 2:47, Lucas Wiman wrote:
> The main way to speed this up is to have system C continue from the last
> residue that it is known that system A and B agree upon.
The way I looked at it, the PrimeNet server only has to store _one_
(64 bit) residue for each exponent in progress. As others have
pointed out, shifting files >> 10 MB in size across slow dial-up
links isn't going to be popular, but you can't have C continue from
the last residue agreed by A and B, unless the agreed residue is
known to the PrimeNet server.
10000 users by 16 MB per file = 160 GB of disk space - I think Scott
might have to invest in a new disk array!
> Or, possibly
> even better (though more error prone) would be to have A and B recalculate
> from last agreed upon residue, and see if they now agree.
Now, that's a possibility. But suppose they don't, again. It's
possible that this could happen if one of the systems was sufferring
from an esoteric hardware bug (possibly common to both systems, but
they'd be running different offsets, so the FFT data would differ).
My "inefficient" scheme also allows reasonably quick recovery from
one of the systems disconnecting from the project.
>
> Won't this mean systems constantly getting interupted in the middle of an
> exponent segment? Or would the systems only continue on one segment when
> they finish the current one?
No - if I've exponent x suspended & I'm working on exponent y ( > x),
then I just wait until I'm checking in y anyway, when I may get a
message to continue x (or some other exponent(s)). If I don't, and y
is now suspended too, I need another exponent to start work on.
If I find I have several exponents all of which are now OK to
continue, I just pick the numerically lowest one to work on next.
>
> This makes sense, though it might not be needed. This scheme would work
> best on people willing to stay with GIMPS for the decade required to
> finish the range. Many of these people have (fast) networks with lots of
> computers on them. The check/double check computers might be right next
> to each other, owned, and run by the same person.
A couple of points here:
(1) Can anyone honestly commit to a project for a whole decade?
(2) I honestly think it's better if the two computers working on a
particular exponent are _not_ owned/operated by the same person. This
precaution removes the possibility of one deranged individual
"contaminating" the project results by "forging" results.
Regards
Brian Beesley
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