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2003-12-12, 22:46   #12
nfortino

Nov 2003

3×5×11 Posts

Quote:
 Originally posted by nitro My few 2.4 P4's spit that out per WEEK, if they didn't suck at factoring I might switch them over....
Except TF is not credited the same as LL testing is. I don't know the exact conversion, but it is discussed at http://mersenne.org/ips/faq.html under Why is factoring CPU time not ranked with equal weight as primality (Lucas-Lehmer) test CPU time?

 2003-12-12, 23:51 #13 PrimeCruncher     Sep 2003 Borg HQ, Delta Quadrant 2·33·13 Posts To get people to do LL tests. George figures if you get more credit for LL, then more people will do it. And P4s don't suck at TF. My Celeron 2.0GHz does one about every 32 hours and is my best machine. Last fiddled with by PrimeCruncher on 2003-12-12 at 23:52
 2003-12-13, 00:20 #14 dsouza123     Sep 2002 2×331 Posts With trial factoring, for 64 bits and below, P4s or Celerons with SSE2 are very slow for their clock speed but at 65+ they are superb. A few of them could really boost TF ranking, maybe with specific optimizations the Athlon64s/Opterons will be able to be superb at both, and become super trial factoring CPUs.
 2003-12-13, 00:36 #15 PrimeCruncher     Sep 2003 Borg HQ, Delta Quadrant 2·33·13 Posts Pehaps. But for purely TF purposes I think Celeron will be the best buy for some time. It has the best SSE2 optimizations (obviously, since Intel made it), it has the speed, and it has a low price tag. A Celeron node can be had for $150 where a similar P4 node would be at least$250 and I don't want to think about Athlon64/Opteron. But you are correct that they add a lot of power. Given 0.105 CPU years per current TF (is that still the figure, dsouza123?) my Celeron will push over 28 CPU years per year Note to self: complete farm and buy more nodes ASAP!! Just goes to show that the answer is ALWAYS D: MORE BOXEN!! Last fiddled with by PrimeCruncher on 2003-12-13 at 00:37
 2003-12-13, 00:48 #16 dsouza123     Sep 2002 29616 Posts The .105 figure varies somewhat depending on the TF but it is very close. I agree with you, until things change alot, right now the Celeron with SSE2 gives an excellent (perhaps best) bang for the buck at trial factoring.
2003-12-13, 01:56   #17
nitro

Feb 2003

7810 Posts

Quote:
 Originally posted by PrimeCruncher To get people to do LL tests. George figures if you get more credit for LL, then more people will do it. And P4s don't suck at TF. My Celeron 2.0GHz does one about every 32 hours and is my best machine.
P4's suck at anything less than ~64 bits, above that they wipe the floor with everything.

I just sent a P4 to get a couple of factoring exponents, the 2.4GHz reckons it will go from 60 to 67 bits in just over 28.5 hours...

2003-12-13, 03:06   #18
PrimeCruncher

Sep 2003

2BE16 Posts

Quote:
 Originally posted by nitro P4's suck at anything less than ~64 bits, above that they wipe the floor with everything.
Yes, but 57-64 is an extremely small portion of the TF. The stuff that takes a long time on current PCs is 65 and above, which P4s are optimal for. It's a small sacrifice for a huge gain.

 2003-12-13, 04:49 #19 Complex33     Aug 2002 Texas 5·31 Posts Too bad the server can't split the TF's up between the instruction sets... below 64 to non SSE2 machines and above to SSE2 machines. I tried to convince a friend who has a couple of dual processor Athlons and a dual 3 gig Xeon that he should physically transer factoring work between the two along these lines, too much work, oh well :) Then again if there were just a P-1 factoring assignment I'd have him doing that.... 12 gigs of ram between these boxen is good
2003-12-13, 14:07   #20
PrimeCruncher

Sep 2003

2·33·13 Posts

Quote:
 Originally posted by Complex33 Too bad the server can't split the TF's up between the instruction sets... below 64 to non SSE2 machines and above to SSE2 machines.
Maybe we should ask Old man PrimeNet for that feature in v5.

2003-12-13, 14:40   #21
nfortino

Nov 2003

3×5×11 Posts

Quote:
 Originally posted by Complex33 Too bad the server can't split the TF's up between the instruction sets... below 64 to non SSE2 machines and above to SSE2 machines.
A variation of the first part of that can, and in my opinion should, be done with an edit to prime95. There are some computers doing TF that take forever to complete it. In fact, some take so much time, that the LL front wave overtakes them. When this happens, it defeats the entire purpose of TF. The v4 server works with the FactorOverride=n command, so all that needs to be done is tell prime95 to automatically put this command in for really slow machines at a reasonable bound. That way, the slow machines can take the easy parts of TF, and the fast ones can finish the job. The only complexity I see is how to make sure the slow machine does not continuously take the same exponent which has already been factored past its bound, and then release it, and take it again.

Last fiddled with by nfortino on 2003-12-13 at 14:41

 2003-12-14, 22:58 #22 QuintLeo     Oct 2002 Lost in the hills of Iowa 26×7 Posts The V4 server does NOT work well with the Factoroverride option - there have been a lot of "stuck exponent" problems that appear to be attributed to that. Scott is aware of it already, though - I suspect v5 will be more ... robust ,,, when dealing with that option. I think it would take a Prime program change to say "well, if this is an Athlon do the TF up to 2^64 then hand it back in for a P4 or P4-Celeron to work on the rest of the way" automagically.

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