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BOINC 6.10.58 incorrect running time estimation
Raistmer:
:D ;D
Jason G:
FWIW, fixing the client side DCF logic, and adding & switching to per app DCFs, weren't enough by themselves, and tended to oscillate/overshoot/freakout, even though not as badly.
The later modded Boincs use a hybrid PID controller core (from Engineering control systems theory) tuned to damp oscillation sufficiently, but allow a quick rise under normal work variation. It's considered hybrid, rather than pure PID, because it still uses heuristics for safety with overflows etc.
That's been fairly stable here for quite a while, which means if later I switch to a simpler 'fuzzy' equivalent, lock DCFs'aDCFs to 1.0 & try manipulating flops instead as suggested by Joe, there should be the capability to use some more human readable/adjustable controls. (neither DCF or other fudge factors, or PID controls are considered human readabl, whereas fuzzy parameters usually are).
That, using the app flops, could end up more acceptable for future client integration (than per app DCF), though I am very wary of trying to introduce client side improvements that would disguise the fairly severe server side flaws at this stage.
Jason
[Edit:] found a good description that I was looking for, illustrating the difference between pure heurisitic based control, versus PID (proportional-Integral-Derivative) based control: http://en.wikipedia.org/wiki/Gaze_heuristic
--- Quote ---Gaze heuristic
From Wikipedia, the free encyclopedia
The gaze heuristic is a heuristic employed by people when trying to catch a ball. Experimental studies have shown that people do not act as though they were solving a system of differential equations that describe the forces acting on the ball while it is in the air and then run to the place at which the ball is predicted to hit the ground. Instead they fixate the ball with their eyes and move so as to keep the angle of the gaze either constant or within a specific range. Moving in such a fashion assures that the ball will hit the catcher.
--- End quote ---
. PID control 'works' but isn't very human like, so can be difficult to tune, and sometimes looks illogical (even when tuned correctly & working), and tends to become clunky if you have to add a lot of heuristics around it. Either full fuzzy, or fuzzy enhanced PID, should end up better resembling more natural human-like control & tuning, so 'feel' better, even though effectively doing the same job as PID probably to similar mathematical quality.
SciManStev:
From what I'm reading here, it looks like these lousy limits are here to stay. I must admit I find that quite disturbing. Rats!
Steve
Jason G:
--- Quote from: SciManStev on 08 Feb 2012, 05:40:08 pm ---From what I'm reading here, it looks like these lousy limits are here to stay. I must admit I find that quite disturbing. Rats!
Steve
--- End quote ---
I'd say probably not 'here to stay', other than project side seems to be focussed on some other mysterious stuff lately, rather than tying up loose ends with the main project or Beta. What those other things might be though, is open to guessing ;)
SciManStev:
--- Quote from: Jason G on 08 Feb 2012, 05:48:52 pm ---
--- Quote from: SciManStev on 08 Feb 2012, 05:40:08 pm ---From what I'm reading here, it looks like these lousy limits are here to stay. I must admit I find that quite disturbing. Rats!
Steve
--- End quote ---
I'd say probably not 'here to stay', other than project side seems to be focussed on some other mysterious stuff lately, rather than tying up loose ends with the main project or Beta. What those other things might be though, is open to guessing ;)
--- End quote ---
I'll take even the smallest bit of optimism as a very positive step. My GPU's ran dry again today. I have a few GPU units on board now, but it does get frustrating going from full to the limits to empty in just a few hours. I can only hope this will eventually get fixed.
Steve
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