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Rapid Increase in RAC

Rapid Increase in RAC

Message boards : Number crunching : Rapid Increase in RAC
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old_user353238

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Credit: 3,581,078
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Message 36437 - Posted: 21 Mar 2009, 11:31:48 UTC

Odd.

Over last week, my RAC has increased dramatically by about 40%. Normally, flat out 24/7, the machines\' total RAC ranges from 5,300 to 5,700.

Today (or after yesterday\'s update at the new later UK time), RAC has continued to increase, day by day, and is now at 7,757.

1) Credits increased by a typical 5,419 between last two credit updates - so no \"bonuses\" there.
2) Don\'t see similar increases with other team members (run custom team stats, so have checked last week\'s backup snapshot).
3) Only time RAC can jump significantly is after a period of detached network (e.g. on return from holiday when models left running).
4) Fastest machine has increased to 3,869 from a normal peak of 2,600. Even throttled this one back a couple of weeks ago.
5) Slowest machine is now at 1,261, normally around 500.

At first I assumed this may have been due to recent changed CPDN update time until I checked other people (point 2 above).

Main account page here.

Is this a clue? Have checked each PC\'s RAC again. The only one that has only just started a HadAM3P shows a typical RAC of 526.
The other three have been running these new models since they became available. Probably a red herring.

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old_user183856

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Message 36438 - Posted: 21 Mar 2009, 13:05:08 UTC

I also am getting a big increase RAC. It started when i began running the new AMP3 models.
Also it doesn\'t appear to be showing up at BoincStats only in the boinc manager ???

Recent average credit RAC (according to Climate Prediction) 1,291.92602
Recent average credit RAC (according to BOINCstats) 1,070.93927

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old_user353238

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Message 36441 - Posted: 22 Mar 2009, 10:05:38 UTC

Yes, the increase must be related to the new models.

This morning my total is now exceeded 8k and the quickest
machine over 4k - the 38th top computer!

Will check out other team members who have also run HadAM3P models.

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Eirik Redd

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Message 36447 - Posted: 23 Mar 2009, 16:10:21 UTC - in response to Message 36441.  

Yes, the increase must be related to the new models.

This morning my total is now exceeded 8k and the quickest
machine over 4k - the 38th top computer!

Will check out other team members who have also run HadAM3P models.



The RAC is obviously wrongly computed. My C2D 8400 at 3.5G is doing 2 hadam3p\'s every 2 days. That is clearly about 1900 creadits per day.

But the RAC is showing at 3800 and climbing.

Eric
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Message 36448 - Posted: 23 Mar 2009, 17:00:10 UTC
Last modified: 23 Mar 2009, 17:04:48 UTC

There are two separate issues here.

1. The CPDN server has recently failed to export our credits to the stats sites on several days. When this happens the server later exports an accumulation of credits. This causes a rapid and atypical rise in RAC. This high RAC then reduces slowly because it\'s a decaying average. Many members are probably at the moment seeing atypically high RAC values. If the CPDN server now behaves correctly and the credit export script runs regularly, after another two or three weeks we will again see our typical and real RAC values.

2. The HadAM3P models do offer more credits than other models in some cases. (The number of credits per model is always the same.) The higher credit level compensates for the very large uploads and downloads.

The higher credits also compensate for the fact that on some computers these models do not run fast at all. This is especially the case if members don\'t read the warnings in the forum News threads and allow multi-core computers to process many HadAM3Ps simultaneously. They slow each other down. We have seen the web pages of a member\'s hyperthreaded computer running 6 of these models side-by side. The models are advancing like snails at 24 sec/timestep! This member must be receiving less credit than if he only ran other model types.

If possible don\'t use all a computer\'s cores for these models. Run them alongside other model types.
Cpdn news
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old_user294426

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Message 36452 - Posted: 24 Mar 2009, 8:50:21 UTC

Yes. there is obviously something miscalculating.
My nice straight line for Host Total (on statistics page) has continued at a much less steep angle.
But the Host Average is rocketing upwards every day.
Average declined steadily from 830 on Feb22th to 730 on Mar16th
while Total rose steadily from 585,000 to 601,600 (755 per day).
Average shot up from 730 on Mar16th to 1,160 on Mar23rd
while Total only rose (fairly steadily) from 601,600 to 603,900 (329 per day).

Although it is going to apparently settle down again in 3 or 4 weeks, it would be nice if the calculation could take account of a \"restart\" of calculation after a server failure.

Keith

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BarryAZ

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Message 36455 - Posted: 24 Mar 2009, 15:17:01 UTC - in response to Message 36448.  

Note, it did this again yesterday -- I guess we will see if this was simply a one day glitch later today....




1. The CPDN server has recently failed to export our credits to the stats sites on several days. When this happens the server later exports an accumulation of credits. This causes a rapid and atypical rise in RAC. This high RAC then reduces slowly because it\'s a decaying average. Many members are probably at the moment seeing atypically high RAC values. If the CPDN server now behaves correctly and the credit export script runs regularly, after another two or three weeks we will again see our typical and real RAC values.



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Message boards : Number crunching : Rapid Increase in RAC

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