Message boards : ATLAS application : credits for runtime, not for cputime ?
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Klaus

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Message 31003 - Posted: 24 Jun 2017, 6:09:22 UTC

To decrease my cpu-temperature i decrease the cpu usage from 90 % to 45 %.
The runtime and credits for tasks are increasing. My average credit doesn't decrease since 10 days!
My question: credits for runtime, not for cputime ?
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Message 31031 - Posted: 25 Jun 2017, 4:30:05 UTC - in response to Message 31003.  

From what I can see, you have only decreased the CPU throttling, so you can still run 8-core tasks on your 8-core computer.
Indeed the credit allocation is based on run time, and not CPU time (that was mentioned by David Cameron in a thread in old ATLAS project). So it seems that the reduced efficiency in completing a single task is not affecting the credit allocation!
We are the product of random evolution.
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Klaus

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Message 31032 - Posted: 25 Jun 2017, 5:34:30 UTC

In BOINC-manager/opinions/calculation settings i reduced the value for use cpu-time less than ... This was the only change i made. Where you can see this, i don't know. Perhaps you can believe it.
My profession is engeniering and I do not understand why there are the same credits for calculating a WU in 1 h or in 2 to 7 h (cpu-time is the same). Scientists need a lot of results in a short time, so I think it is better to give more credits for a short calculation-time.
(In the last 40 years my income depends on results, not on beeing there)
This is to think over.
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computezrmle

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Message 31033 - Posted: 25 Jun 2017, 6:08:12 UTC - in response to Message 31032.  

In BOINC-manager/opinions/calculation settings i reduced the value for use cpu-time less than ... This was the only change i made. Where you can see this, i don't know. Perhaps you can believe it.

From your log:
2017-06-23 12:25:58 (4820): Setting CPU throttle for VM. (45%)



... (In the last 40 years my income depends on results, not on beeing there)
This is to think over.


If you rent a flat you pay it monthly regardless if you sleep there or not.
If you rent a car you pay per day regardless if you drive it or leave it at the parking site.
If a BOINC project allocates your computing resources you get "paid" in credits regardless of the project's efficiency.
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Klaus

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Message 31034 - Posted: 25 Jun 2017, 6:50:57 UTC

Thanks for the the extra lesson.
You are right in all points.
But I get "paid" in credits regardless of my computer's efficiency.
This is to think over.
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computezrmle

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Message 31035 - Posted: 25 Jun 2017, 8:04:48 UTC - in response to Message 31034.  

Discussions about credit calculation are always very emotional.
I have a very personal opinion about it that I don't want to share here.

Reduced to a very simple technical perspective you may read the BOINC documentation.
This may at least make it clear why it cannot be solved on the fly.
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Klaus

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Message 31036 - Posted: 25 Jun 2017, 10:22:52 UTC

For credids can nobody buy anything, so calculation of credit is no mainproblem.
Reading the BOINC documentation shows to me, that the fairness is a highly complex problem.
I'm not satisfied, but I do not know a solution for everybody.
When my roomtemperature decrease, when there are tasks in the queue i will speed up my cpu as previously.
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djoser

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Message 31163 - Posted: 28 Jun 2017, 18:17:55 UTC - in response to Message 31036.  

Do i understand this right?

Let's say i would want to max out my credit for Atlas-tasks.
So the best would be to limit Atlas to crunch only single core tasks not multicore, right?


For credids can nobody buy anything...


That's not quite correct! See my signature for more infos.

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computezrmle

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Message 31171 - Posted: 29 Jun 2017, 6:46:28 UTC - in response to Message 31163.  

Do i understand this right?

Let's say i would want to max out my credit for Atlas-tasks.
So the best would be to limit Atlas to crunch only single core tasks not multicore, right?

In your case probably not as your 2-core setup seems to be nearly perfect.
At least on this host:
https://lhcathome.cern.ch/lhcathome/show_host_detail.php?hostid=10486800

If you calculate the ratio cputime/(ncores*walltime) you get values between 96.5 % and 98.0 % for your last valid ATLAS results.
There would not be much room for a performance boost if you would run 2 concurrent VMs in a 1-core setup.
Instead it would lock roughly 2 GB more RAM that can be used now by your OS.
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djoser

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Message 31172 - Posted: 29 Jun 2017, 7:33:31 UTC - in response to Message 31171.  

There would not be much room for a performance boost if you would run 2 concurrent VMs in a 1-core setup.


Thanks for your answer!

But if credits are granted for runtime, not cputime then running two single-core tasks concurrently should give twice the amount of credits than one two-core task, correct?

Or what am i missing here?

djoser.
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Crystal Pellet
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Message 31175 - Posted: 29 Jun 2017, 9:14:17 UTC - in response to Message 31172.  

Or what am i missing here?

djoser.

Nothing.

You're right. It's up to you to configure your system(s) to your needs.

ATLAS is the best sub-project in the LHC-project for fixed credits, at least for tasks/jobs from the same batch.
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computezrmle

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Message 31181 - Posted: 29 Jun 2017, 12:02:11 UTC - in response to Message 31172.  

There would not be much room for a performance boost if you would run 2 concurrent VMs in a 1-core setup.


Thanks for your answer!

But if credits are granted for runtime, not cputime then running two single-core tasks concurrently should give twice the amount of credits than one two-core task, correct?

Or what am i missing here?

djoser.

Without looking into the server code I guess that ATLAS solves this issue by calculating a new flops value for the host:
new_flops = original_flops * n_cpus

This way the n_cpus gets represented in the credit calculation algorithm.

It may have been Laurence or David Cameron who mentioned in an old thread that credit calculation is based on walltime.
This ensures that volunteers get rewarded for providing their resources even if the application hangs in an idle loop.
Sorry I can't find the reference at the moment.
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David Cameron
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Message 31196 - Posted: 30 Jun 2017, 11:28:43 UTC

There is a long discussion on this topic on the old ATLAS@Home forum

In conclusion: running single-core tasks gives you more credit, but it's not easy to fill a machine with single-core tasks because BOINC requires the full n-cores memory for each one (even if it doesn't use it).
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marmot
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Message 33176 - Posted: 30 Nov 2017, 15:12:00 UTC
Last modified: 30 Nov 2017, 15:39:31 UTC

Labor is one of the cornerstones for valuation of services/item production and CPU labor(cycles) is what LHC, or any other BOINC project, is receiving.

If LHC is using 8 CPU's and only giving credit for 1 CPU when the other 7 could be used by other projects that are also offering credit, then the payment system is predatory.

I know the argument can be made that the efficiency in performance means faster throughput and so payment is equivalent but... that's not what my data sets from actual measuring is proving.

Single core ATLAS is giving out 1500% to 2000% greater credit per core as the 8 core jobs and even 100% more than the most efficient 4 core.

For comparison, the 2 core Theory performed ~10% better than 1 core WU's and the 8 core Theory WU's (while having 33% CPU inefficiencies) still paid only ~15% worse than a 1 core WU. All tests done on the same machine and compared to another identically configured machine with similar results.

If the multi-core implementations of Theory are able to pay nearly equivalent credit per CPU core claimed then ATLAS should be able to do the same and the 8 core jobs are an order of magnitude worse in payment per core.

I was shocked to see that it's approximately 9x better to run 8 single core ATLAS than to run 3x 8 multicore ATLAS.
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David Cameron
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Message 33198 - Posted: 3 Dec 2017, 21:52:36 UTC - in response to Message 33176.  

As far as I understand credit is based relative runtime compared to the estimated runtime, not on absolute runtime. Therefore if you have been running 8-core tasks for some time then suddenly switch to single core, they run 8 times longer than expected so they get massive credit. But if you keep running single core the estimated runtime adjusts up over time and so the credit decreases.

Also I think Theory tasks work differently in that they have a fixed runtime independent of the number of cores - the WU keep pulling tasks until the time is up. ATLAS tasks have a pre-determined number of events to process so have a different runtime for different core numbers.
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Message boards : ATLAS application : credits for runtime, not for cputime ?


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