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Old 2016-12-12, 23:57   #1
Siegmund
 
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Default P-1 stage 1 only

I have a couple of older/slower/not-continuously-used laptops, which are set to do P-1 factoring. They do just fine during stage 1. They are 'unhappy' (run hot, slow, etc) during stage 2, and sometimes run into memory issues. This isn't as-such prime95's "fault", as it is how much of memory hogs new browsers have become...

But the effect of it is that this type of machine is out there; using the CPU for trial factoring is no longer recommended; and the memory demands of Stage 2 are a problem.

I would love to be able to do P-1 stage 1 only, and then hand off these exponents to machines with more memory. Better for everyone, really, since they will get factored deeper if given to someone with more memory too.

It would be nice to have a way to automate the handoff. And to tell prime95 what I plan to do, when it computes the bounds.

I realize this applies to only a small subset of machines. But thought I would put the idea out there, in case anyone has any ideas how easy it might be to implement this new work type -- in effect splitting P-1 into two tasks, much like each bit level of factoring is its own task. (Bandwidth and storage have become cheap enough that providing an entire savefile is now practical, at least on the client side.)

Anyone have any thoughts?
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Old 2016-12-13, 01:45   #2
GP2
 
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Quote:
Originally Posted by Siegmund View Post
I would love to be able to do P-1 stage 1 only, and then hand off these exponents to machines with more memory. Better for everyone, really, since they will get factored deeper if given to someone with more memory too.
One problem is that some machines out there are unreliable and have a non-negligible error rate. Any error in stage 1 would mean that effort spent on stage 2 would be wasted.

Unfortunately, other people's older machines are precisely the ones that I would be leery of.

Another issue is that the size of the save file after stage 1 will be about one bit for every digit in the exponent. So a P−1 savefile for an exponent around M80,000,000 will be 10 MB in size. Edit: oops, I mean one bit for every binary digit, so adjust the math accordingly, the size will be even larger.

Not a huge problem if two people arrange to swap files with one another, but it would rapidly get unwieldy in terms of bandwidth usage if you want Primenet to be the central repository for tens of thousands of these.

Last fiddled with by GP2 on 2016-12-13 at 02:31
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