504 Hr work time!?

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Profile Matt

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Message 399 - Posted: 26 Nov 2011, 15:49:38 UTC

One of the work units I received in the last update has an estimated completion time of 504 hrs and 45 min, is that normal?
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Profile Eric Driver
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Message 400 - Posted: 26 Nov 2011, 16:29:57 UTC - in response to Message 399.  

One of the work units I received in the last update has an estimated completion time of 504 hrs and 45 min, is that normal?


No, that doesn't sound right. I would guess that the client calculated the estimated time incorrectly. If you give me a link to the WU, I could look at it closer.

Thanks,
Eric
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Richard Haselgrove

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Message 401 - Posted: 26 Nov 2011, 16:35:00 UTC - in response to Message 399.  

One of the work units I received in the last update has an estimated completion time of 504 hrs and 45 min, is that normal?

It depends what you mean by 'normal'.

Looking at your computer, and specifically the Application details for host 1491, it's clear that you haven't done any work for this project for a little while. As a result, all the tasks you received this morning used applications that your computer hasn't run before - one task for "Get Decics with Bounded Discriminant v2.04" (which you've completed), and three tasks for "Get Decic Fields v1.01" - these will be the ones with the badly-estimated completion time.

Because this is the first time you've run these applications, the server doesn't have any information about how well the tasks run on your machine. But your machine itself will have some knowledge of the project in general, because of the 'bounded - v2.02' jobs you've run in the past. I'm guessing that you've ended up with a high 'Duration Correction Factor' from that earlier run, which is skewing the estimate for the new work.

The 'bounded - v2.04' tasks are notoriously variable in their run time - you got one of the quicker ones.

The 'decic - v1.01' tasks are (in my experience) less variable, but in general longer: using somewhat faster CPUs than yours, I'm seeing a variation between roughly 15 hours and 30 hours - so I'd be surprised if your tasks ran for more than 50 hours in the end.

Another curiosity is that these tasks usually show around 50% progress soon after they've started, then slow down dramatically. But they do get there in the end, and even speed up a bit as they approach the finishing line.

In short, the "normal" thing is that the initial runtime estimate for BOINC tasks has to be taken with a pinch of salt.
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Richard Haselgrove

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Message 402 - Posted: 26 Nov 2011, 16:41:11 UTC - in response to Message 400.  

... If you give me a link to the WU ...

Click on his name, then computers - view, then tasks, to end up at

All tasks for computer 1491
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Profile Matt

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Message 403 - Posted: 26 Nov 2011, 17:04:55 UTC - in response to Message 401.  

Ok, thanks for the explanation. I'll just let the work unit run and see what happens.
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Message 404 - Posted: 26 Nov 2011, 17:52:38 UTC

Hello, it's me again. Just thought I'd let you guys know that not long after the work unit started it jumped to 50% complete with an estimated completion time of 60 hours.
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ChertseyAl

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Message 405 - Posted: 26 Nov 2011, 18:38:48 UTC - in response to Message 404.  

The 2 that I have/had (on VERY slow hosts) jumped to 50% very quickly and started climbing steadily.

One had got to 80-something percent and suddenly finished after around 39 hours - Got decent credit for it too, about time, I thought I was jinxed ;)

The other is 71% after 45 hours, and I'm guessing it will finish at around 60 hours.

Only using these old hosts for this project as they are my junk test machines with BOINC 6.10.30 and 6.12.32 which I don't want on any other machines, and I don't think this project works properly (regarding Run Time) with older versions.

Al.
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Profile Eric Driver
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Message 406 - Posted: 26 Nov 2011, 20:13:40 UTC - in response to Message 404.  

Hello, it's me again. Just thought I'd let you guys know that not long after the work unit started it jumped to 50% complete with an estimated completion time of 60 hours.


I treat each pass through the search loop equally with respect to computing the percentage complete. But in reality, the beginning and end of the search are faster than the middle. Thats why you see a quick jump (to about 50%) at the start of the search.

For those who are interested in more details, read on...
The core of the search algorithm uses a series of tests to filter out the candidate fields. The outer part of the search region corresponds to fields whose polynomial coefficients are larger than usual, and these get filtered out very quickly in the earlier tests. On the other hand, the middle of the search region corresponds to fields whose polynomial coefficients are smaller- these fields make it to the inner most tests which involve computing field discriminants and factoring large integers, and these tests are much more computationally intensive.
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Profile Eric Driver
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Message 407 - Posted: 26 Nov 2011, 20:16:39 UTC - in response to Message 401.  

Thanks Richard for explaining that. I figured it had something to do with the DCF.
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frankhagen

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Message 408 - Posted: 26 Nov 2011, 23:40:51 UTC - in response to Message 405.  
Last modified: 26 Nov 2011, 23:41:25 UTC

The 2 that I have/had (on VERY slow hosts) jumped to 50% very quickly and started climbing steadily.

One had got to 80-something percent and suddenly finished after around 39 hours - Got decent credit for it too, about time, I thought I was jinxed ;)


of course you did - eric got rid of creditnew.. ;)
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