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steveplanetary

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Message 8826 - Posted: 17 Jan 2010, 15:00:59 UTC

I just checked the Properties of my current task in the BOINC Manager GUI and found the CPU time to be less than the Elapsed time, again. I'm going to report this on the BOINC Message Boards too, but it only happens on E@H. Here are the particulars:

1/17/2010 1:18:09 AM Einstein@Home Restarting task h1_1098.70_S5R4__286_S5R6a_1 using einstein_S5R6 version 301

CPU Time: 10:11:24
Elapsed Time: 09:48:18
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Message 8829 - Posted: 18 Jan 2010, 12:46:09 UTC - in response to Message 8826.  

As this is Cosmology@home not Einstein@home, this should be posted on Einstein's message board for them to see it.

Have you noticed the problem on Cosmology?

I can't say that I have taken much notice of the CPU and elapsed times, I might just have to take a look.
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steveplanetary

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Message 8832 - Posted: 18 Jan 2010, 20:40:50 UTC - in response to Message 8829.  
Last modified: 18 Jan 2010, 20:56:57 UTC

Sorry. I posted on the wrong forum. In answer to your question, no, I have never seen this with C@H, only E@H. I also posted a message regarding this problem on the BOINC message boards and received this reply:

"Sometimes BOINC looses the Elapsed time, whole or part, but not the correct accumulated CPU time (which is what is the part of the base for credit computation claim). Reported several times and not seen this scheduling wrecking behaviour for quitesome time now, having progressed to 6.10.25 alpha."


Cheers, Steve
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sygopet

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Message 8838 - Posted: 21 Jan 2010, 10:37:34 UTC

In BOINC Manager>Tasks, for (as far as I know) ALL projects, and for any task that has started, the properties button will show "elapsed time" and "CPU time" and (as you would expect) elapsed is always slightly greater than CPU time.

For a task that is running there is also the CPU time at the last checkpoint.
It is this latter time which, for Cosmology, is often an hour or more adrift - leading to potential waste of processing time if something goes wrong - and we really do need more built-in checkpointing to overcome that.

All other BOINC projects, in my experience, checkpoint at much more frequent intervals so the "CPU time at the last checkpoint" is never more than a minute or two behind "CPU time".

Elapsed time is another matter and the difference between this and CPU time depends how busy your computer is with other things; I find typically less than 5% for my projects, for completed tasks. But I can't give you the figure for Cosmology because that information is not given.
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Forums : General Topics : CPU Time Less Than Elapsed Time