Program reaches 25% in a minute, then takes 3 hours to finish.


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Questions and Answers : Windows : Program reaches 25% in a minute, then takes 3 hours to finish.

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Michael Schwebs
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Message 1550 - Posted: 25 Jun 2004, 0:25:59 UTC

I was wondering if this was a glitch. Sometimes, when it starts a new workunit, it instantly starts searching for Spikes/Guassians/Triplits.

In about a minute, it says its 25% done, then starts doing the Fast Forum transform.

the remaining 75% takes about 3 hours.

I was wondering if a programmer messed up somewhere.

Profile Ageless
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Message 1556 - Posted: 25 Jun 2004, 0:33:32 UTC

Nope, this is by design.

Unless you have a workunit filled with "noise", but you'd be able to check that in the stderr of the unit once returned to the site.


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Jord™
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Profile David Dyer-Bennet
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Message 2103 - Posted: 25 Jun 2004, 20:21:29 UTC - in response to Message 1556.

> Nope, this is by design.

Well, it's a bad design. I know it's hard to make a well-behaved progress indicator when multiple steps are being done, or when the actual work is very non-uniform; but this grotesque degree of non-linearity *by design* is just wrong.

I've had my own runins with implementing progress indicators at work, and been told that by others, sorry if my satisfaction of getting to pass it on is too evident :-).

Heffed
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Message 2139 - Posted: 25 Jun 2004, 21:05:12 UTC - in response to Message 2103.

> Well, it's a bad design. I know it's hard to make a well-behaved progress
> indicator when multiple steps are being done, or when the actual work is very
> non-uniform; but this grotesque degree of non-linearity *by design* is just
> wrong.
>
> I've had my own runins with implementing progress indicators at work, and been
> told that by others, sorry if my satisfaction of getting to pass it on is too
> evident :-).

HeHe... You'd totally freak out if you saw how it behaves with debug active. ;-)

Profile Shaktai
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Message 2242 - Posted: 26 Jun 2004, 3:02:42 UTC - in response to Message 2139.

>
> HeHe... You'd totally freak out if you saw how it behaves with debug active.
> ;-)

Aahh, debug. Such fond memories of unpredictable activity. :-)

Since the intial nature of a work unit is not known until it is processed, it is very difficult to develop a truly predictable progress indicator. There is no way of knowing how long various aspects of the actual work unit will take. Typically they start off fast and then slow down, but each and every one is different. The nature of the work (calculations) is not strictly linear, but more a matter of erratic peaks (lots of information to process) and valleys (little information to process) that vary dramatically from one work unit to another. Very difficult to predict.

John McLeod VII
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Message 2254 - Posted: 26 Jun 2004, 4:32:32 UTC - in response to Message 2242.

> >
> > HeHe... You'd totally freak out if you saw how it behaves with debug
> active.
> > ;-)
>
> Aahh, debug. Such fond memories of unpredictable activity. :-)
>
> Since the intial nature of a work unit is not known until it is processed, it
> is very difficult to develop a truly predictable progress indicator. There is
> no way of knowing how long various aspects of the actual work unit will take.
> Typically they start off fast and then slow down, but each and every one is
> different. The nature of the work (calculations) is not strictly linear, but
> more a matter of erratic peaks (lots of information to process) and valleys
> (little information to process) that vary dramatically from one work unit to
> another. Very difficult to predict.
>
> <a> href="http://www.boinc.dk/index.php?page=user_statistics&userid=153364"> [/url]

Profile Thierry Van Driessche
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Message 2314 - Posted: 26 Jun 2004, 9:37:37 UTC
Last modified: 20 Jul 2004, 13:53:15 UTC

When Boinc was in the starting phase, the CPU timings against percentage done were even stranger then it is now.
See this graph.

Greetings from Belgium.

Questions and Answers : Windows : Program reaches 25% in a minute, then takes 3 hours to finish.

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