claimed vs. granted credits

> I'm no expert on this, but this is just my observations over time.
>
> Generally, the validator waits for two or three completed results before it
> awards any credit.
Three. And they have to be valid, i.e. contain no memory dumps or other non-numeric stuff.
At this point, it picks the lowest of those two/three
> claimed credits and awards it to all the completed WUs.
At this point, it does a "matching" of every result against each other, and
determines the "best guess" (remember that in the real world, there is no
identity of numbers....)
The "best guess" is declared the "canonical result" which additional results
can be matched against, and if they fit, they get exactly the same credit
as the ones that matched before.
Non-matching results are declared INVALID and dropped.

If I read my
> information right, this is theoretically how BOINC is designed to grant
> credit.
There are lots of adjustable things...

> However, there are some flukes. Juerschi's is a great example:
> http://einstein.phys.uwm.edu//workunit/307539
>
> Notice that the awarded credit was the lowest amount between the two units
> (bottom listings) that reported on 19 Jan 2005. Then the final result (3rd
> from top) was reported on 21 Jan 2005. From looking at this, the validator
> probably awarded credit after receiving the first two results.
This should be considered an error: the matching algorithm takes three results to determine the canonical result. If there are less than three, the validator will wait for more. If a result proved to be INVALID from the very beginning (file unreadable at a certain level, including bad characters inside...) another job is generated to ensure the "quorum" can be reached.

Then, when the
> third one came in two days later, it was awarded the same amount as had
> already been credited to that WU.
All results that match the canonical one are assigned the same credit.

I've seen cases where this happened in my
> own WUs. I received one from P@H to crunch somewhere around 15 Jan or so,
> which had received two results back in December, both of which had been
> granted credit. I came in somewhat under their claimed credits, but I was
> award the same amount they had received. I don't have that info available to
> me right now, but I could try and look it up later if anyone was interested.
The P@H validator may work completely different!

> Now having said all of this, just rooting around on a couple of the examples
> given seems to indicate something fishy to me. Juerschi's WU indicates two
> similar machines (Athlon XP 2600) whose only differences are one was a mobile
> (laptop) chip and the other appears to be desktop, which returned similar
> benchmark results. Yet, somehow the desktop smoked the laptop by almost a
> factor of 10 (4,969.91 secs vs 45,241.64 secs). Seems to me that something may
> be wrong in the validatator code somewhere that accepted an incomplete result
> from the "really fast" host as a completed WU.
This should not happen.
There may be a huge difference in the last stage of the code though that would
produce different run times: memory usage. The laptop probably has less RAM and had to swap a lot. Whether this additional time would be included in the credit claim, I don't know for sure.
Another source for time differences may be a spurious reset of accumulated CPU time which is being investigated right now... judging from the phone discussion from the desk next to me...

> And finally, this is no attempt to trash or contradict Bernd - so no offense
> to the staff! I'm just throwing in what I seem to remember as the way the
> system supposedly works, along with a few semi-educated guesses.
... which may or may not be wrong. Thanks a lot!

S