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Message boards : General Topics : ncpus simulation and credit system

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Luigi R.
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Joined: 31 Jan 16
Posts: 17
Credit: 898,822
RAC: 7
Message 20778 - Posted: 1 Feb 2016, 12:52:46 UTC
Last modified: 1 Feb 2016, 13:22:05 UTC

Hello, I'm mainly running boinc2docker app.

I was trying to use more ram and/or getting almost 1 task working while the others are stuck at 0.100% (downloading...).

My cpu is 8-threads... so simulating 16 ncpus would have been fine to run 2 tasks simultaneously. Anyway I started simulating 32 ncpus (4 tasks) and my host is working well, but I noticed my RAC quadruplicated! Is this normal? I would not like to pass for a cheater.



Edit: oh, now (13:00 UTC) I'm getting only twice the ordinary RAC.

Profile Marius
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Joined: 29 Jun 15
Posts: 427
Credit: 4,276
RAC: 0
Message 20780 - Posted: 1 Feb 2016, 13:28:39 UTC - in response to Message 20778.

Hi Luigi, no worries about being mistaken for a cheater. You're seeing normal effects of CreditNew, the credit system used by camb_legacy and camb_boinc2docker. This is because job credits are based on elapsed time, not CPU time. After a few more jobs, as you're already seeing, the credits per job will settle back down towards average.

That said, I'm not sure why you're wanting to run multiple camb_boinc2docker jobs concurrently, since they're multi-threaded and will automatically use all of your cores.

Luigi R.
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Joined: 31 Jan 16
Posts: 17
Credit: 898,822
RAC: 7
Message 20786 - Posted: 1 Feb 2016, 14:15:10 UTC
Last modified: 1 Feb 2016, 15:14:32 UTC

I noticed that cpu use is lower when a task starts (for 10-20 seconds). It will use 50-75% instead of 200%. So I tried to fill this gap with at least 1 more task. I wanted the remaining % of my cores was used by other tasks.
Total should be 800%.

Here my processes (4 tasks when they are running at all). Total: 781.2%


Here 1 task (the last one) is stuck at 0.100% on BOINC, 3 tasks are running.

There is a little boost on 1st and 2nd tasks. Total: 774.8%

That said, I'm not registering great differences, maybe I've no way to evaluate differences if credits are not reliable. I think I will return to 1 task at time soon or later.

Luigi R.
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Joined: 31 Jan 16
Posts: 17
Credit: 898,822
RAC: 7
Message 20790 - Posted: 1 Feb 2016, 15:30:09 UTC

I tried to run all threads for 1 task (as usual for this project).

Here while the task is stuck at 0.100% on BOINC. Total: 45.2% of 800%!


Here while the task is running. Total: 731.6%



I don't know if I discovered warm water, but my host appears to take advantage of running 4 tasks simultaneously.

Message boards : General Topics : ncpus simulation and credit system