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-   -   768k Skylake Problem/Bug (https://www.mersenneforum.org/showthread.php?t=20714)

Gordon 2016-01-05 16:44

[QUOTE=Madpoo;421257]And remember that half the people you meet have below average intelligence. :smile:[/QUOTE]

...and a few are in the top 2% :hello:

tha 2016-01-05 17:42

I ran two tests today. Both ran 8 separate threads on 4 physical cores concurrently.

The first test ran four exponents in the 2M range in the threads 1 through 4 and four exponents in the 14M range in the threads 5 through 8.

This test run was aborted after the exponents in the 2M range completed.

The second test run consisted of 8 exponents in the 2M range. However in the worktodo file it was specified that they have to run in FFT2=768K mode.

In the first test all four assignments completed successfully. In the second test two assignments failed and 6 completed correctly.

To me this is very eerie similar to the FDIV bug. Most divisions were successful, some failed.

[CODE]
[Tue Jan 5 13:26:31 2016]
= M2000093 is not prime. Res64: D174884B5080EBB8. We8: 79F2D864,1146114,00000000
= M2000147 is not prime. Res64: 934D1CC6B0837C4E. We8: 1FB6A4DD,390140,00000000
= M2000227 is not prime. Res64: F77D1A92737F343C. We8: 36018BA5,348922,00000000
= M2000281 is not prime. Res64: A7D6528C3DFFBD48. We8: B888E4F9,966220,00000000

[Tue Jan 5 18:02:15 2016]
= M2000147 is not prime. Res64: 934D1CC6B0837C4E. We8: 1FBED035,942308,00000000
= M2000353 is not prime. Res64: EEEE1F405891B800. We8: 1A695479,1419216,00000000
= M2000281 is not prime. Res64: A7D6528C3DFFBD48. We8: B8B2A946,553931,00000000
= M2000321 is not prime. Res64: 4E7D677A2432CA95. We8: 2F7E4FC3,1192667,00000000
* M2000227 is not prime. Res64: 8D3112D7CBD7863E. We8: 0412C104,676436,00000000
= M2000381 is not prime. Res64: 97E22ADFEBBA19CA. We8: DD86F310,1479688,00000000
* M2000371 is not prime. Res64: 02075B9EF9ABEE13. We8: A5E56644,1180696,00000000
= M2000093 is not prime. Res64: D174884B5080EBB8. We8: 79E588AA,1846728,00000000
[/CODE]

tha 2016-01-05 17:51

[QUOTE=Gordon;421306]...and a few are in the top 2% :hello:[/QUOTE]

I assume there are above average fellow mensans around in this forum.
:hello:

chalsall 2016-01-05 18:37

[QUOTE=tha;421312]I assume there are above average fellow mensans around in this forum.[/QUOTE]

Statistically likely.... :hello:

chalsall 2016-01-05 23:44

ROFL...

So, I had to jump through hoops to get this message posted on the Intel Forum:

[QUOTE]Hi Mike.C. from Intel.

I do hope your engineering department is working this.

You might want to get your public and investor relations departments on this really soon now....[/QUOTE]

That message is "Currently being Moderated".

chalsall 2016-01-06 00:12

[QUOTE=chalsall;421339]That message is "Currently being Moderated".[/QUOTE]

Coolness. [URL="https://communities.intel.com/message/361811"]The message was released from moderation.[/URL]

Intel... Please understand. We want to work with you.

But the silence has been deafening.

LaurV 2016-01-06 01:57

[QUOTE=Gordon;421306]...and a few are in the top 2% :hello:[/QUOTE]
well, statistically, those are 1 in 50... we don't think we have so many friends... :sad:

chalsall 2016-01-06 23:38

Intel has admitted the bug!
 
Great job everyone!

This was posted on the [URL="https://communities.intel.com/thread/96157?start=15&tstart=0"]Intel Forum[/URL] this afternoon by DAVID ORLICH SOLANO, apparently an Intel representative:

[QUOTE]Hello All,

Intel has identified an issue that potentially affects the 6th Gen Intel® Core™ family of products. This issue only occurs under certain complex workload conditions, like those that may be encountered when running applications like Prime95. In those cases, the processor may hang or cause unpredictable system behavior. Intel has identified and released a fix and is working with external business partners to get the fix deployed through BIOS.[/QUOTE]

Yet another example that persistence, and the scientific method, works! :smile:

Edit: Oh, and that George writes _awesome_ code.... :tu:

kladner 2016-01-07 03:35

[QUOTE=chalsall;421422]Great job everyone!

This was posted on the [URL="https://communities.intel.com/thread/96157?start=15&tstart=0"]Intel Forum[/URL] this afternoon by DAVID ORLICH SOLANO, apparently an Intel representative:



Yet another example that persistence, and the scientific method, works! :smile:

Edit: Oh, and that George writes _awesome_ code.... :tu:[/QUOTE]

This is an impressive accomplishment! Thanks and Praises to all who contributed to the knowledge of this bug, and to those who rattled cages to get Intel to pay attention. :tu:

AGM 2016-01-07 04:37

Wow, that went pretty quick and smooth. I was expecting months of battling with them. :)

LaurV 2016-01-07 06:33

Well, actually they are pretty reasonable if we can make them see the reason. This turned out very well, for them too, as they can fix it without a recall. Which for me is bad for two reasons, first because I have no skylake, and second, if i would have one, i missed the opportunity to exchange it for a 6990X... :razz:

(still dreaming that i buy an intel cpu which is bad, and it takes months for them to accept it, during which time they still come out with few more powerful/expensive versions, but then they can't fix my bug and recall all, and they make it up to me by replacing it with the best they have, where the bug is fixed, which is 10 times more expensive and 20 times faster... - if you wake me up I will kill you!)


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