Prime95 version 29.4

[ET_]

I am enjoying a free ride on a cheap cloud server, having 5 core hours of AVX @2.3GHz and the remaining 19 at a tweaked power (about 5%-6% of the normal).

Although slow, the server worked fine until today, when I got the following (repeating) message:

[Work thread Dec 18 11:17] Possible hardware errors have occurred during the test! 1 ROUNDOFF > 0.4.
[Work thread Dec 18 11:17] Confidence in final result is excellent.

I am running PRP-CF on exponents in the 64265XX range.
Questions:

1 - Is it a possible (cheap) server issue or a FFT boundary issue?
2 - Should I unreserve the exponent (I'm still at 25% and in the "slow" tide)?
3 - Should I revert to some less stresssing work for the CPU, like trial-factoring?

Luigi

[ET_]

Originally Posted by Mark Rose

Yes. The PRP test is able to detect memory problems and it will report, something like this:

[Work thread Dec 14 16:12] Iteration: 61480000 / 75757575 [81.09%], ms/iter: 6.939, ETA: 27:37:15
[Work thread Dec 14 16:12] Hardware errors have occurred during the test!
[Work thread Dec 14 16:12] 15 Gerbicz/double-check errors.
[Work thread Dec 14 16:12] Confidence in final result is excellent.

I don't have the sentences highlighted in red.
Also the "hardware thinghie" wording is different.

And when I restarted the program, I had the message:

[Work thread Dec 18 12:24] Resuming Gerbicz error-checking PRP test of M64265XX

[Prime95]

Originally Posted by ET_

1 - Is it a possible (cheap) server issue or a FFT boundary issue?
2 - Should I unreserve the exponent (I'm still at 25% and in the "slow" tide)?

1) My guess is cheap server.
2) Continue on - that is the point of Gerbicz error checking.

[ET_]

The exponent 6426523 ended up being "Unverified (Reliable)", with error code 00000100 and a message saying "Computer hardware check recommended. Possible hardware errors occured during PRP test of M6426523 -- ".
The Gerbitz test was correctly run, and the following (smaller) exponent does not show (till now) any hardware problems.

Finger crossed.

[moebius]

This is VERY GOOD!!!

[Dec 18 23:59] Iteration: 75690000 / 75699408 [99.98%], ms/iter: 36.999, ETA: 00:05:48
[Dec 18 23:59] Hardware errors have occurred during the test!
[Dec 18 23:59] 15 Gerbicz/double-check errors, 1 ROUNDOFF > 0.4.
[Dec 18 23:59] Confidence in final result is excellent.
[Dec 19 00:06] M75699409 is not prime. Type-4 RES64: 2399B098FED4DF02. Wg4: 81556197,45940480,00F00100

75699409

[R. Gerbicz]

Originally Posted by moebius

This is VERY GOOD!!!

[Dec 18 23:59] Hardware errors have occurred during the test!
[Dec 18 23:59] 15 Gerbicz/double-check errors, 1 ROUNDOFF > 0.4.
[Dec 18 23:59] Confidence in final result is excellent.

It is even catching FFT multiplication errors, or (very unlikely) bug in the FFT code.
Still not many people are using this new feature http://mersenneforum.org/showthread.php?t=22796.

[ixfd64]

Something strange just happened. I'm doing P-1 factoring on an old Windows XP machine and noticed that Prime95 did not continue to stage 2 after stage 1 completed. It only started the GCD step when I stopped and restarted the worker thread.

[Dec 20 23:48] M84865621 stage 1 is 99.68% complete. Time: 90.472 sec.
[Dec 20 23:50] M84865621 stage 1 is 99.73% complete. Time: 90.556 sec.
[Dec 20 23:51] M84865621 stage 1 is 99.78% complete. Time: 90.703 sec.
[Dec 20 23:53] M84865621 stage 1 is 99.83% complete. Time: 90.632 sec.
[Dec 20 23:54] M84865621 stage 1 is 99.88% complete. Time: 93.313 sec.
[Dec 20 23:56] M84865621 stage 1 is 99.94% complete. Time: 88.540 sec.
[Dec 20 23:57] M84865621 stage 1 is 99.99% complete. Time: 88.393 sec.
[Dec 20 23:59] M84865621 stage 1 is 100.00% complete. Time: 94.614 sec.
[Dec 21 00:01] M84865621 stage 1 is 100.00% complete. Time: 97.427 sec.
[Dec 21 00:02] M84865621 stage 1 is 100.00% complete. Time: 93.984 sec.
[Dec 21 00:04] M84865621 stage 1 is 100.00% complete. Time: 97.137 sec.
[Dec 21 00:05] M84865621 stage 1 is 100.00% complete. Time: 93.610 sec.
[Dec 21 00:07] M84865621 stage 1 is 100.00% complete. Time: 97.245 sec.
[Dec 21 00:09] M84865621 stage 1 is 100.00% complete. Time: 96.892 sec.
[Dec 21 00:10] M84865621 stage 1 is 100.00% complete. Time: 95.887 sec.
[Dec 21 00:12] M84865621 stage 1 is 100.00% complete. Time: 92.649 sec.
[Dec 21 00:13] M84865621 stage 1 is 100.00% complete. Time: 94.918 sec.
[Dec 21 00:15] M84865621 stage 1 is 100.00% complete. Time: 93.742 sec.
[Dec 21 00:17] M84865621 stage 1 is 100.00% complete. Time: 129.542 sec.
[Dec 21 00:19] M84865621 stage 1 is 100.00% complete. Time: 120.094 sec.
[Dec 21 00:21] M84865621 stage 1 is 100.00% complete. Time: 138.607 sec.
[Dec 21 00:24] M84865621 stage 1 is 100.00% complete. Time: 143.351 sec.
[Dec 21 00:26] M84865621 stage 1 is 100.00% complete. Time: 126.266 sec.
[Dec 21 00:28] M84865621 stage 1 is 100.00% complete. Time: 134.494 sec.
[Dec 21 00:30] M84865621 stage 1 is 100.00% complete. Time: 120.805 sec.
[Dec 21 00:32] M84865621 stage 1 is 100.00% complete. Time: 137.120 sec.
[Dec 21 00:35] M84865621 stage 1 is 100.00% complete. Time: 139.006 sec.
[Dec 21 00:37] M84865621 stage 1 is 100.00% complete. Time: 138.002 sec.
[Dec 21 00:39] M84865621 stage 1 is 100.00% complete. Time: 117.075 sec.
[Dec 21 00:39] Worker stopped.
[Dec 21 00:40] Worker starting
[Dec 21 00:40] Optimal P-1 factoring of M84865621 using up to 512MB of memory.
[Dec 21 00:40] Assuming no factors below 2^76 and 2 primality tests saved if a factor is found.
[Dec 21 00:40] Optimal bounds are B1=640000, B2=8480000
[Dec 21 00:40] Chance of finding a factor is an estimated 2.76%
[Dec 21 00:40] Using Pentium4 FFT length 4480K, Pass1=896, Pass2=5K, clm=4
[Dec 21 00:40] Starting stage 1 GCD - please be patient.
[Dec 21 00:45] Stage 1 GCD complete. Time: 303.138 sec.
[Dec 21 00:45] Using 478MB of memory.  Processing 8 relative primes (0 of 480 already processed).
[Dec 21 00:46] M84865621 stage 2 is 0.13% complete.
[Dec 21 00:48] M84865621 stage 2 is 0.21% complete. Time: 131.798 sec.
[Dec 21 00:50] M84865621 stage 2 is 0.29% complete. Time: 122.391 sec.

Is this a bug?

[Prime95]

Originally Posted by ixfd64

Is this a bug?

Sure looks like one.

[TheJudger]

Seems I'm a bit late on upgrading to v29.4, guess this has already been reported, anyway here is some console output of v29.4b5 64bit Linux. 4 workers, 1 thread per worker:

[Worker #1 Dec 30 01:57] Running Jacobi error check.  [Dec 30 01:57] Running Jacobi error check.  [Dec 30 01:57] Running Jacobi error check.  [Dec 30 01:57] Running Jacobi error check.  [Dec 30 01:57] Sending interim residue 30000000 for
 M79xxxxxx
[Comm thread Dec 30 01:57] Sending interim residue 25000000 for M79xxxxxx
[Comm thread Dec 30 01:57] Done communicating with server.
[Worker #2] Passed.  Time: 23.227 sec.
[Worker #4] Passed.  Time: 23.278 sec.
[Worker #1] Passed.  Time: 23.282 sec.
[Worker #3] Passed.  Time: 23.287 sec.

• 1st line: missing new lines and missing "Worker #X" or "Comm thread" for following messages within the same line.
• 4th to 7th line ("Passed" Jacobi error checks): no timestamps inside the square brackets

Oliver

[Prime95]

Build 7 uploaded.

What's new:

P-1 is marginally faster in stage 1. Unfortunately, old P-1 save files from stage 1 are no longer any good.

M77232917 will no longer beep like crazy when run to completion

The service versions were also built.

[Madpoo]

Originally Posted by Prime95

Build 7 uploaded.

What's new:

P-1 is marginally faster in stage 1. Unfortunately, old P-1 save files from stage 1 are no longer any good.

M77232917 will no longer beep like crazy when run to completion

The service versions were also built.

I updated the download page with the new details... good stuff.