From: Lucas Wiman <[EMAIL PROTECTED]>
Subject: RE: Mersenne: Multiple residues - enhancing double-checking
Date sent: Wed, 4 Aug 1999 03:26:48 -0400 (EDT)
> True, but if the system is malfunctioning then the errors should start
> early.
If the program is buggy, too. (v17 ghost is here)
> > Just for example, every 10% along the way, it'll send it's current residue
> > to the Primenet server.
>
> I'm guessing that you mean a certain amount of the residue. Sending in
> 10 2meg files for *each* exponent in the 20,000,000 range would get very
> unwieldy, and inconvenient for people and primenet.
Aaron has said the same as me, using better grammar :-) .
Obviously, only a few bytes are needed.
> Of course, this would only help if we were running more one test for the
> same exponent at the same time [...]
The simultaneous checks are interesting only on the first
stages of v19 or other "new" testers. When a complete double
check will last 6 months in a new FFT size, while the author waits
for a result, a lot of people will be using it.
[...]
> That is to say when
> one computer finishes to X%, it reports its 64-bit residue to primenet, and
> waits for the second computer working on the same LL test to do the same.
> Until the other (slower) computer reports in, the (faster) computer works on
> another exponent.
Not at all. The first-time check goes its way, but reporting
partial residues to coordinator / primenet from time to time. Later,
often when first LLTest was finished long time ago, somebody
receives:
Double-Check:
M23780981,64,863FF87,678676AA,FF637BC,[...],CRC:9923FDA.
The partial residues corresponds to X iterations first, 2*X iterations
second, etc. X is fixed for all participants. Or use percentages
instead, as Aaron said. An absence of a residue between two
colons means that is unknown. With a so long and sensitive data
streams (200 bytes typical) the CRC is a must to detect accidental
modifications of the Worktodo file.
This schema makes possible simultaneous checking,
though. But the start-stop mechanism you describe has little
sense.
> This would speed up the entire project, but it would slow down the individual
> exponent, which would make people mad :(.
My schema only would speed double checking. The first-
time LLTest process is untouched, except of the reporting of
intermediate partial residues.
> As I pointed out above, the error rate should increase with the square of the
> exponent (plus change). This means that if 1% have errors at 7mil, 22% will
> have errors at 30mil.
That's the matter with the idea: an estimate of time saved
(on double checking!) should be made. The authors of tester apps
should estimate the early bug catching features of this schema,
too. Then, decide if its worth or not.
I'm doing double checking. I think about my computer
running for 6 months when the error is on the second week. Argh!
Saludos
Oscar Fuentes.
P.D.: I promise to improve my English ;-)
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