credits?

hookedonsaturn
hookedonsaturn
Joined: 5 Jul 07
Posts: 9
Credit: 846
RAC: 0
Topic 192945

I am not sure if i understand how the credits work
reading on it if i understand right the same job is sent out to 2 different machines and if the result is the same you get the credits for that job.But if the results differ because 1 machine is windows base and the other linux base then the job gets sent to another machine and which ever machine the 3rd one agrees with then they get the credit. When this 3rd machine is used is it a randomly generated choice of linux or windows or is linux chosen over windows?

thank you

Gary Roberts
Gary Roberts
Moderator
Joined: 9 Feb 05
Posts: 4,653
Credit: 23,007,822,377
RAC: 30,306,890

credits?

Quote:
... if the result is the same you get the credits for that job.

Yes.

Quote:
... if the results differ ....

If the results differ for whatever reason, a third machine will be chosen to break the deadlock. If this machine also produces an inconsistent result, it is possible for even more machines to be used to attempt to reach a consensus. As soon as two machines agree within fairly strict limits, the result will be validated and those machines which are not close enough will be excluded. This is quite irrespective of the OS. The selection of the "decider" machine is not based in any way on OS.

However, having said that, it is true that one of the major reasons why results do not agree sufficiently for validation to occur is that the maths libraries of the different OS's (not just Windows and Linux) give different answers to the same problem. The admins are working very hard to find a way to resolve this.

If you take a look at the server status page you will find the number of invalid results recorded. It is a lot higher than it should be but still relatively modest when compared to the number of valid results also recorded there. In fact, the majority of Linux/Windows or Linux/MacOS or Windows/MacOS confrontations do give a valid result.

Quote:
When this 3rd machine is used is it a randomly generated choice of linux or windows or is linux chosen over windows?

Strictly, I guess, the answer is neither :).

It's not really a random choice nor is it a choice for Linux. However, because of the preponderance of Windows boxes, the deciding machine is far more likely to be a Windows box than any other OS. This is a bit unfair for those who run Linux :).

Hopefully the cross-platform validation problem will be resolved in the near future.

Cheers,
Gary.

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