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Old 2014-08-13, 07:12   #1
TheMawn
 
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May 2013
East. Always East.

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Default Lots of roundoff errors

Hey, folks.

I've been getting a number of roundoff errors in a DC. I wouldn't be heartbroken if the test came out bad since it's a smaller exponent (less wasted time) but I'd still like to get to the bottom of this.

I've attached a screenshot of the worker in question.

Here's the bits of results.txt relevant to the exponent in question.

Code:
[Tue Aug 12 00:32:29 2014]

Trying 1000 iterations for exponent 32562559 using 1680K FFT.
If average roundoff error is above 0.24236, then a larger FFT will be used.
Final average roundoff error is 0.23838, using 1680K FFT for exponent 32562559.

[Tue Aug 12 07:50:20 2014]

Iteration: 6557188/32562559, Possible error: round off (0.4375) > 0.40
Continuing from last save file.
Disregard last error.  Result is reproducible and thus not a hardware problem.
For added safety, redoing iteration using a slower, more reliable method.
Continuing from last save file.

[Tue Aug 12 22:27:40 2014]

Iteration: 7679973/32562559, Possible error: round off (0.4375) > 0.40
Continuing from last save file.

[Wed Aug 13 01:03:36 2014]

Iteration: 7679973/32562559, Possible error: round off (0.4375) > 0.40
Continuing from last save file.
Disregard last error.  Result is reproducible and thus not a hardware problem.
For added safety, redoing iteration using a slower, more reliable method.
Continuing from last save file.
I was having some strange stuttering problems (audio and video) during a Civ5 round with friends. I was going to stop a Prime95 worker, but when I saw all of this crap, I stopped everything altogether and rebooted. All technical issues vanished.

When I started my worker up again, I took the screenshot.

7:50 on Tuesday is some random time of the morning.

22:27 is when we started the round.

1:03 on Wednesday is when I started everything up again.


The part that scares me is "2 roundoff errors of which 1 is repeatable"

EDIT: Now that I think of it, the 22:27 and 1:03 errors are probably the same ones. I think I stopped the program before it had the chance to double-check the questionable iteration.
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Last fiddled with by TheMawn on 2014-08-13 at 07:13
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