Forum > GPU crunching
x38g reports
Josef W. Segur:
--- Quote from: perryjay on 24 Jun 2011, 10:27:25 am ---Jason, does this new build do anything about clearing up the -12 issue? I just found this WU marked invalid, too many bugs. http://setiathome.berkeley.edu/workunit.php?wuid=764389127 I was the only one running the V 0.38g and the only one to complete it without getting -12.
--- End quote ---
AFAIK x38g and x32f have the same improvements relative to triplet handling, they allow 1 more than stock before committing suicide. Of the 3 triplets found, two must have been in the same array; stock fails on that, x3xx Lunatics doesn't.
Joe
Jason G:
--- Quote from: Josef W. Segur on 24 Jun 2011, 12:22:09 pm ---
--- Quote from: perryjay on 24 Jun 2011, 10:27:25 am ---Jason, does this new build do anything about clearing up the -12 issue? I just found this WU marked invalid, too many bugs. http://setiathome.berkeley.edu/workunit.php?wuid=764389127 I was the only one running the V 0.38g and the only one to complete it without getting -12.
--- End quote ---
AFAIK x38g and x32f have the same improvements relative to triplet handling, they allow 1 more than stock before committing suicide. Of the 3 triplets found, two must have been in the same array; stock fails on that, x3xx Lunatics doesn't.
Joe
--- End quote ---
Yep, that's Joe's extension, which continues to serve very well. Ultimately, I have as a goal to converge CPU & GPU results as much as possible/practical/reasonable, even though the nature of floating point arithmetic & the hardware it is executed on pretty much guarantees some amount of variation when different algorithms are used for the same set of computations. That means several of the GPU kernels will end up being reengineered to some degree, and in the meantime can expose cross-platform limitations that were instilled in the original CPU code as well (as with spikes accuracy) due to not having forseen that vastly different hardware would one day be trying to match results.
This kindof juggling is proving to have annoying side effects for the interim period, though my hope is that when seti@home V7.x is released, that the intermediate pain will have proved worthwhile, even if there are still wrinkles to iron out.
One thing to keep in mind, with classical control system redundancy techniques like this used in 'real' systems like aircraft, is that the redundancy is usually specified to have different authors & hardware manufacturers, and that they must agree within accepted variation. With the inconclusives & subsequent reissues we are seeing even between results that look pretty much the same to all external visible features, we are seeign that validation mechanism 'working' as it should.
My current standing is that we are seeing legacy application limitations in combination with new hardware variations add up to 'a circus' of marginally close answers. I feel that the base design change decisions for legacy work & the intent to converge cross platform results moving into V7 will prove the right direction, though I am also certain that some new architectures present further difficulties yet to be divined.
Jason
perryjay:
Jason, in case you miss it in the NC forum, I've decided to go back to two at a time. Not long after I posted over there I started getting sluggish again. No down clock but everything running very slow. I shut down Firefox but no change, so I also shut down Thunderbird. Still nothing so I shut down SETI and closed BOINC manager. When I restarted BM and SETI everything came back to normal. I let it run for awhile with no problem but I get the feeling my little 450 doesn't like running three work units at a time 24/7. It seems to like to take a little break every now and again. I'll see how it likes two at a time again and let you know how it goes.
Jason G:
OK, no worries. Responded over there. If it happens with 2 as well we might have to dig at that as well, though is probably just related to things that need to be done next anyway.
perryjay:
Well over 24 hours now and everything is going along great. Guess I was just pushing the limit by running three at a time.
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