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World Community Grid Forums
Category: Support
Forum: BOINC Agent Support
Thread: Credit calculation affected by old results |
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Thread Status: Active Total posts in this thread: 12
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
I've upgraded the CPU on one of my machines and the credit it's claiming went up a little, but nothing like what it should have.
Most documentation says that the client calculates credit by comparing the benchmark figures with the amount of CPU time taken. However, there are obviously some other elements (irrelevant under the circumstances) such as host_expavg_credit maybe? How long will this bias take to go away? |
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Sekerob
Ace Cruncher Joined: Jul 24, 2005 Post Count: 20043 Status: Offline |
I've done a test the day before related to some credit and performance research. It took about 15 Ready to Report clearing cycles before the 'claims' side normalized. The servers 'remember' which acts as a protection against sudden drops of benchmark ratings and persistent under claimers which happens semi frequently. The up are too rare to worry about.
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
So that would be 15 WUs before it stops under-claiming? That's hideous.
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Sekerob
Ace Cruncher Joined: Jul 24, 2005 Post Count: 20043 Status: Offline |
Have explained why that logic is used.
----------------------------------------Presently the change of a CPU type is not an item considered a reason to record a new device. That could have been forced, but then there are members who baulk at yet another unmergeable device at WCG (Maybe after the complete gutting of the old UD Database out of the WCG system). can't have it all.
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
Presently the change of a CPU type is not an item considered a reason to record a new device. True. That would be a terrible solution. If someone simply upgrades their machine, it would make sense for the old data to simply be ignored. It's pretty obvious that, if the benchmark results are 2.5 times what they used to be, the historical data is meaningless. |
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Sekerob
Ace Cruncher Joined: Jul 24, 2005 Post Count: 20043 Status: Offline |
Sorry, not. My tests proofed that BOINC Benchmark v Performance can be tremendously influenced. And there of course are those to consider who use home brew clients that use e.g. a 3x integer multiplicator ;>)
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
My tests proofed that BOINC Benchmark v Performance can be tremendously influenced. I'm sure they vary a lot between different machines. But when the same machine is suddenly much faster, it's pretty clear that using old data for it is pointless.However, it is probably mitigated on WCG by the non-standard method of calculating credit. The upgraded computer won't be anywhere near its recent average, so it'll be ignored in favour of whatever the other computer claims. |
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JmBoullier
Former Community Advisor Normandy - France Joined: Jan 26, 2007 Post Count: 3716 Status: Offline Project Badges: 
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I've upgraded the CPU on one of my machines and the credit it's claiming went up a little, but nothing like what it should have. I am not sure of what you mean. Do you mean that you expected each WU to be claiming more credit than before, or do you mean that this machine is not getting more credits per day after the upgrade? The purpose of the credit system is to have each WU credited the same amount, whether it was computed by a slow processor or by the fastest one. Simply said, it is the computation which is rewarded, not the speed. Therefore if your CPU was awarded a fair amount per WU before the upgrade there is no reason that it would be awarded more per WU after. The benefit of the upgrade is that it should crunch more of these WUs each day. Cheers. Jean. |
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
 What Kremmen says is that the historical bench mark is far below his new bench mark, but it will take several days for the server to start allowing him to claim his new points per hour. All the special rules that keep credit claims from absurd mistakes are working against his new CPU. But after a few days, it should all work well. To handle this special case, we would have to check for a change in CPU type, then have some special code to reset all the historical values as though it were a new computer. And this would be in the BOINC server code, which propagates to all the other projects. Well, eventually we should do this, but the credit system has gotten so convoluted there would probably be a number of special cases to change. Meanwhile, we have BOINC 6 to roll out. My feeling is that we should let David Anderson decide the priority on this change. Lawrence |
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JmBoullier
Former Community Advisor Normandy - France Joined: Jan 26, 2007 Post Count: 3716 Status: Offline Project Badges:
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OK Lawrence, I was not aware of those other sanity rules which seem a little redundant or even inconsistent with some other ones. But as you say the crediting system has gone through so many steps that it is not simple to fairly cover all possible circumstances.
----------------------------------------And before the recent change aiming at reducing the number of duplicate devices Kremmen's update would have probably resulted in the creation of a new device, avoiding this problem. Anyway, if some rules are forbidding him from claiming enough his claim should be too low when compared to the other addressees of his WUs and he has a good chance of finally getting the credits he deserves at this last stage, no? Cheers. Jean. |
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