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Old 2017-12-27, 07:02   #12
ewmayer
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Quote:
Originally Posted by Prime95 View Post
A day after Christmas a computer has reported a new Mersenne prime. Unlike the numerous CudaLucas false positives we've had over the last few years, this one shows promise.
Quote:
Originally Posted by Madpoo View Post
Otherwise, my verification won't technically count as a double-check since it's another Prime95 run and we'd still want one with another program (mprime, cudalucas, cllucas, etc).
When I read George's OP his wording led me to understand that the prime-reporting run was done using CuLu ... but Aaron, you say it was in fact a Prime95 (or mprime) run?

@Serge: I don't recall if Gord Palameta (a.k.a. GP2) did timings for 16-or-more-core C5 instances, and if so, how those compared to the EC2-instance timings you got for your verify run of the last prime 2 years ago. I'll try to dig up some numbers tomorrow.

Last fiddled with by ewmayer on 2017-12-27 at 07:04
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Old 2017-12-27, 07:27   #13
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A positive PRP test result for the candidate you are testing, would be a relativity quick test with a very strong indication that you do not have a false-positive.
Would it not?
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Old 2017-12-27, 07:48   #14
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Originally Posted by a1call View Post
A positive PRP test result for the candidate you are testing, would be a relativity quick test with a very strong indication that you do not have a false-positive.
Would it not?
I don't see the advantage of using a PRP test in this context ... no faster than LL, and on the highly-reliable (typically with ECC RAM) systems usually used by George & Aaron for their 'first look' DCs the kinds of system glitches the Gerbicz error check is designed to catch are unlikely to come into play. Also, if the initial run used LL, using LL for the DC allows direct cross-comparison of intermediate Res64s, if the user's logfile is available. (At least I would hope it would work this way.)

Even if the original run didn't output interim residues in the manner I describe, when George/Aaron do their DC they set the flag to do so, which means if their run also says 'prime', then the official independent-software DCs can do such interim-residue cross-matching ... this is especially important for the GPU clients, which are very fast but error-prone, to be able to tell if the GPU DC has gone off the rails, in which case it is restarted from the most-recent interim savefile whose Res64 matches the Prime95 DC one.

Last fiddled with by ewmayer on 2017-12-27 at 07:52
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Old 2017-12-27, 10:00   #15
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Quote:
Originally Posted by Madpoo View Post
What's the fastest GPU out there now for LL testing... Titan of some flavor?
Titan V. Probably will do this in under 18 hours. IIRC, TheJudger posted some benchies on it.
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Old 2017-12-27, 10:04   #16
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Originally Posted by Uncwilly View Post
Did the e-mail system work?
Of course not. Chalk up yet another failure for this particular PHP code. I've asked Aaron and James to investigate.

What's weird is I copied that code for the recent PRP changes. I've successfully received several Mersenne-cofactor-is-PRP emails over the last few months.

Quote:
Did the residue masking work? (And is there a clue somewhere?)
The quick look around I did on the web site showed nothing of interest. Perhaps someone here can find a web page that doesn't mask the result as well as it should.

Quote:
Can we assume that this is a WR or should we assume that this is a Double Check? Also, I would assume, based upon the times your are talking about, this is not in the 100M digit range.
You may assume anything you like

Last fiddled with by Prime95 on 2017-12-27 at 10:10
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Old 2017-12-27, 10:05   #17
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Quote:
Originally Posted by TheJudger View Post
CUDA 9.0, CUDA driver 384.98, CUDALucas 2.05.1 (SVN rev. 99)

Benchmark FFT sizes './CUDALucas -cufftbench 2048 32768 20'
Code:
Device              Tesla V100-PCIE-16GB
Compatibility       7.0
clockRate (MHz)     1380
memClockRate (MHz)  877

  fft    max exp  ms/iter
<snip>
 4375   80897867   0.9595
 4608   85111207   0.9649
 5184   95507747   1.0124
Oliver
Assuming 82M expo, Titan V should complete it in under 24 hrs.
EDIT:- The above benchmark is for a Tesla V100 which ought to be faster than Titan V.

Last fiddled with by axn on 2017-12-27 at 10:07
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Old 2017-12-27, 10:08   #18
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@Ernst: Yes, the initial run was done with Prime95. Madpoo's unofficial DC is also with prime95.

An mlucas run and a CudaLucas run would be a good idea. Volunteers?
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Old 2017-12-27, 10:24   #19
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Quote:
Originally Posted by Prime95 View Post
Prime95 version 28.9 was used. Thus, no Jacobi checking during the run or at the end of the run.
Then I'm not the one who found it

As you know, I am maintaining the DoubleMersenne site. It would be nice to know the exponent in advance (once confirmed) to start the sieving (it should be tested up to at least 600T, or 210 CPU/days) and set up the updated pages.

Last fiddled with by ET_ on 2017-12-27 at 10:34
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Old 2017-12-27, 10:29   #20
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Originally Posted by ET_ View Post
Then I'm not the one who found it
So sorry, maybe next time.

I reached the potential discoverer by email. Of course, he/she is traveling and cannot send the last intermediate file to me. We have to wait for madpoo.
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Old 2017-12-27, 11:11   #21
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Quote:
Originally Posted by Prime95 View Post
@Ernst: Yes, the initial run was done with Prime95. Madpoo's unofficial DC is also with prime95.

An mlucas run and a CudaLucas run would be a good idea. Volunteers?
I would like to start a Titan Black run and I could start a mlucas run on a C5 instance, I just need to compile mlucas on it.

The fastest GPU right now is the Tesla P100 and TheJudger might have one, as he has posted benchmarks.

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Old 2017-12-27, 12:11   #22
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Fastest GPU today should be Tesla V100 - TITAN V has "crippled" memory bandwidth and thus should be slower because CUDAlucas is memory bandwidth bound on this type of hardware.

Oliver

Last fiddled with by TheJudger on 2017-12-27 at 12:12
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