Message boards :
Number crunching :
threefold validation
Message board moderation
Author | Message |
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atlov Send message Joined: 11 Aug 12 Posts: 35 Credit: 32,718,664 RAC: 34 |
Hi folks! I noticed WU 1833335409 received 3 valid results, although the two hosts 7261736 and 6782743 supplied results within their deadlines, so at first glance I don't see a reason why to send the WU out to a third host. I'm not quite sure, but this WU could have been in my validation inconclusive folder for some time, so maybe the first two results differed above some numerical threshold and the third result validated both by being inbetween the other two? Any comments on this? |
Rasputin42 Send message Joined: 25 Jul 08 Posts: 412 Credit: 5,834,661 RAC: 0 |
I have something similar. It is marked validated in my account, but a third user is still processing it. WHY? WUhttp://setiathome.berkeley.edu/workunit.php?wuid=1761966073 |
Donald L. Johnson Send message Joined: 5 Aug 02 Posts: 8240 Credit: 14,654,533 RAC: 20 |
Hi folks! Yes, that appears to be the case. While all 3 valid results had 30 and 30, the lists of signals/strengths are different for the first two, so the WU was ruled "Inconclusive", and sent out for a 3rd. The 3rd errored, and so generated a 4th. The 4th appears to have matched the 1st result, so the 1st became the canonical result entered into the AP science database, but the 2nd was within the tolerances for "weakly similar", so all 3 got credit. Donald Infernal Optimist / Submariner, retired |
atlov Send message Joined: 11 Aug 12 Posts: 35 Credit: 32,718,664 RAC: 34 |
Host 7027212 returned its result after the deadline, so the WU was sent out to the third host. |
Rasputin42 Send message Joined: 25 Jul 08 Posts: 412 Credit: 5,834,661 RAC: 0 |
A computer only knows ones and zeros. How can there be ANY difference in the results at all?(unless there is a computing error) |
Donald L. Johnson Send message Joined: 5 Aug 02 Posts: 8240 Credit: 14,654,533 RAC: 20 |
I have something similar. See my response to your previous question about this Workunit in this thread. Donald Infernal Optimist / Submariner, retired |
Rasputin42 Send message Joined: 25 Jul 08 Posts: 412 Credit: 5,834,661 RAC: 0 |
1st: Why did the user get credit, if the result was submitted after the deadline. 2nd: If a result is validated, why is any ongoing calculation of this task not canceled? It is already validated, so why crunch it again? |
Donald L. Johnson Send message Joined: 5 Aug 02 Posts: 8240 Credit: 14,654,533 RAC: 20 |
A computer only knows ones and zeros. The applications written to process Seti@Home Tasks on different platforms (CPU, GPU, different Operating systems) have some differences based on hardware and OS characteristics, and so sometimes produce slightly different results for the same Task/data set. Jason Gee and Joe Segur have written much better explanations than I can give as to how and why this is. We seem to see it most often when a CPU is paired with a GPU, or when one of the Hosts runs a stock application while the other runs Anonymous Platform. It's just how it is. Donald Infernal Optimist / Submariner, retired |
HAL9000 Send message Joined: 11 Sep 99 Posts: 6534 Credit: 196,805,888 RAC: 57 |
Hi folks! It is likely that the first two failed to validate because they were not "strongly similar", but with the third result they all validated due to being "weakly similar". With the various apps/hardware we do get different rounding & precision values. So this tends to occur from time to time. AstroPulse v7 Windows x86 rev 2721 Nvidia AstroPulse v7 Windows x86 rev 2737 Nvidia AstroPulse v7 Windows x64 rev 2692 CPU SETI@home classic workunits: 93,865 CPU time: 863,447 hours Join the [url=http://tinyurl.com/8y46zvu]BP6/VP6 User Group[ |
Donald L. Johnson Send message Joined: 5 Aug 02 Posts: 8240 Credit: 14,654,533 RAC: 20 |
1st: Why did the user get credit, if the result was submitted after the deadline. I answered that question in the previous thread. 2nd: If a result is validated, why is any ongoing calculation of this task not canceled? It is already validated, so why crunch it again? Probably because the folks who wrote the server software decided that it was not worth the effort to add the extra code (and server processing time/database searches) to send out a notice and cancel the 3rd (or 4th, or....) Task. And other than it takes longer for you to see the Task drop off the BOINC database and your Tasks page, what harm does it do? If this sort of thing happened a LOT, it might make sense, but apparently it only happens once in a blue moon...... Donald Infernal Optimist / Submariner, retired |
Mike Send message Joined: 17 Feb 01 Posts: 34258 Credit: 79,922,639 RAC: 80 |
Its a known issue that GPU apps act different than CPU app on 30/30 after signals are found. Joe can explain better. With each crime and every kindness we birth our future. |
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