20151224, 04:42  #67 
∂^{2}ω=0
Sep 2002
República de California
2×3×11×149 Posts 
Is the error rate really dropping as the exponents get larger, or is that an artifact of the sampling methodology?

20151224, 06:43  #68  
Serpentine Vermin Jar
Jul 2014
29×113 Posts 
Quote:
On the other hand, these larger tests are done by (generally) more reliable systems which may balance things out. FYI, hopefully we'll see a curious "bump" in proven bad results as a direct result of our effort to find these bad CPUs and do doublechecking ahead of the curve. When we find those bad systems, they're still technically unverified until a triplecheck is done, so it may still be a while until those get done. 

20151224, 07:15  #69 
Basketry That Evening!
"Bunslow the Bold"
Jun 2011
40<A<43 89<O<88
7197_{10} Posts 
I believe that's the sampling methodology  those tests simply have been largely not double checked, so anything with zero error code is assumed to be good, even though that's not true.

20151224, 21:00  #70  
Serpentine Vermin Jar
Jul 2014
CCD_{16} Posts 
Quote:
I should clarify that by "non zero" I mean any error code that would mark it as "suspect". There are nonzero errors that are normal... like repeatable rounding errors during the run. I should say "suspect" and "nonsuspect" instead of zero/nonzero. Well, I forget the actual rates, but it was something like that. 

20151224, 21:47  #71  
Serpentine Vermin Jar
Jul 2014
29·113 Posts 
Quote:
If the result is marked "clean" (not suspect), counting up all of the known good/bad results, the odds of it being bad are just a hair under 2%. (I don't consider the stillunknowns when calculating, i.e. I just use (bad)/(bad+good)). Here are the raw stats on those "clean" results: Code:
Unknown Bad Good 648674 29698 1501012 Raw stats: Code:
Unknown Bad Good 5904 31827 27562 Last fiddled with by Madpoo on 20151224 at 21:56 

20151224, 23:07  #72 
Serpentine Vermin Jar
Jul 2014
29·113 Posts 
Another couple data points...
If the error code actually is just "00000000" the odds of it being bad are currently 1.84% The *total* known error rate no matter what the result code = 3.87% Last fiddled with by Madpoo on 20151224 at 23:10 
20151224, 23:26  #73  
"Patrik Johansson"
Aug 2002
Uppsala, Sweden
110101000_{2} Posts 
Quote:
( # known bad LL results ) / ( # known bad LL results + # known good LL results ) A result is known to be bad when two other LL results for the same exponent don't match the result but still match each other. I use the publicly available information at mersenne.org to collect information (Reports>Detailed Reports>LL Results). The green curve is above the red one since I count a number of unverified tests as bad: When there are still unverified exponents in the interval (i.e. there are exponents left, for which there are still not two matching tests), if there are n nonmatching tests for an exponent, I count n1 of them as bad. The red curve does not use the unverified tests at all. ^{1}Not including unverified tests, though, if any. 

20151224, 23:43  #74  
"Patrik Johansson"
Aug 2002
Uppsala, Sweden
424_{10} Posts 
Quote:
Still, a fairly constant error rate at around 4% would mean that the probability per iteration of an error is dropping at the same time as the amount of computations (per iteration) is increasing (due to the larger FFT:s). 

20151226, 20:14  #75 
Just call me Henry
"David"
Sep 2007
Cambridge (GMT/BST)
3^{4}×71 Posts 
It would be interesting to see the graph with fft boundaries added to see if they match the variations in the graph at all.

20151226, 21:11  #76 
If I May
"Chris Halsall"
Sep 2002
Barbados
5^{2}×373 Posts 

20151226, 22:30  #77 
Just call me Henry
"David"
Sep 2007
Cambridge (GMT/BST)
3^{4}·71 Posts 

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