On Sat, 16 Feb 2002 [EMAIL PROTECTED] wrote:
> Is this _really_ a problem, or is it likely to become one in the
> forseeable future? Trial factoring is well ahead of LL testing at
> present, and seems to be still pulling further ahead, despite the
> improvement in the relative efficiency of LL testing vs. trial factoring
> with fairly widespread deployment of P4 systems.
Trial factoring is well ahead of LL testing, but the gap is closing.
Yesterday was the first day in a long time where the net number of
checkouts for factoring exceeded those for first time LL's. That is due
to the fact that one team is having a factoring challenge among their
membership due to begin soon, and large numbers of factoring assignments
are being checked out in preparation. It isn't a trend that is going to
persist. Ongoing, more factoring assignments have to be done than LL
assignments because factoring eliminates a substantial number of exponents
from LL testing.
The situation has improved recently from two earlier surges in LL testing.
One accompanied the discovery of M39, the other was a post-Christmas surge
(GIMPS participants with shiny new fast computers replacing slower ones,
presumably). Many of those who joined up after M39 have dropped out, and
the crest of the wave of their expiries has passed (over 150 assignments
started on Nov. 14th expired in one day, for instance). For awhile, the
balance was around 300 net LL's checked out to 150 factoring assignments.
That has narrowed to around 250 to 200, and sometimes comes fairly even,
although to keep up, GIMPS needs more factoring assignments done than
LL's.
> I would have thought that, in the event that LL testing did start to
> catch up to trial factoring, the first thing to do would be to reduce
> the initial trial factoring depth by 1, then run P-1 and only then
> proceed to do the last bit of trial factoring. In fact on P4 systems it
> might be more economical to stop trial factoring sooner than that.
The cutoffs for those computers set to "do the work that makes the most
sense" can be adjusted to put more computers on trial factoring work if LL
testing starts to overrun trial factoring. The cutoffs could also move
some computers doing first time LL onto doing double checks, although too
much would have the leading edge of DC's running into the trailing edge of
LL's, and I understand that PrimeNet has difficulty with that situation.
Right now DC checkouts are going very slowly, less than 100 a day most
days.
Something that would likely help a lot would be to add factoring
capability and PrimeNet access code to those programs that don't yet have
it so that more computers can reasonably participate.
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