I've not been long involved in GIMPS and noticed the following:-
>So for an exponent like 8027219, you'd save the partial residue at the 10%,
>or 802722th iteration (rounding up or down as normal). Of course, the
>number of iterations varies just slightly from the exponent, but
>whatever...you get the idea.
>From this I understand that it takes around about the same number of
interations as the size of the exponent to establish primality.
I've got several UltraSPARCs I've pressed into service and currently
have 7 exponents checked out being tested with MacLucasUNIX. When I
filled out the manual checkout form I assumed, for lack of better
information, that an UltraSPARC would perform like a Pentium. This
doesn't appear to be at all close to the truth. My first assignment
was for 7902277. The account details indicated this would take 600
hours of CPU on a 270MHz Pentium.
It's doing fractionally more than one iteration every second. That's
judging by the times between checkpoint files at 5000 iterations
between checkpoints. So far it's used 716.7 hours of CPU. At this rate
it's probably done a bit over 2,500,000 iterations or is about one-third of
the way there.
Is this about right for this type of system?
Details:-
Ultra-5 270Mhz CPU, 128Mb RAM
Solaris 7
gcc version 2.8.1
Also, I've tested MacLucasUNIX with the Sun CC compiler using the
-fast option and it's about a third faster than when compiled with gcc,
but there are warnings like:-
The -fast option is unsuitable for programs that require strict
conformance to the IEEE 754 Standard.
Should I be using this option?
Thanks for any help.
Bill Rea, Information Technology Services, University of Canterbury \_
E-Mail b dot rea at its dot canterbury dot ac dot nz </ New
Phone 64-3-364-2331, Fax 64-3-364-2332 /) Zealand
Unix Systems Administrator (/'
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