Forum > GPU crunching
x38g reports
Claggy:
--- Quote from: arkayn on 29 Jun 2011, 07:47:12 pm ---I thought it was the 560's having problems, I have not seen any problems from my little 460.
--- End quote ---
I think the 560's just have bigger problems,
Claggy
Jason G:
--- Quote from: Claggy on 29 Jun 2011, 07:50:09 pm ---
--- Quote from: arkayn on 29 Jun 2011, 07:47:12 pm ---I thought it was the 560's having problems, I have not seen any problems from my little 460.
--- End quote ---
I think the 560's just have bigger problems,
--- End quote ---
and not all 460's & 560's are created equal either, whereas 480's like mine & Steve's are nVidia reference & likely as close to identical as they come, so relatively predictable. It's something that should not reflect in the results when the code is 100% 'right'.
Since some of the newer code in play is specifically written to exploit the superscaler instruction level parallelism for maximum bandwidth on compute capabiiity 2.1, i.e 48 instead of 32 Cuda cores per multiprocessor with an extra warp scheduler, if somethings' being pushed to the limits kernel execution configuration wise then It;s going to show on those cards with harder constraints first.
Jason
Josef W. Segur:
Hmm, I noticed the "Bodgy Best Gaussian" occurred at chirp rate ~63.9958 and the presumably correct one at ~79.3237. So while running the WU with stock 6.95 I periodically checked state.sah to see what would turn up near those rates. Before the first there was a fairly weak "best" captured at chirp -15.88619 with a score of 0.125732, then the bodgy with a score of 1.293129, and the final one had a score of 1.305961. I don't know how to evaluate the 0.98% difference between bodgy and final scores.
AK_v8b_win_SSSE3x.exe has just gotten to bodgy and calculates its score as 1.293091 which is close though I'd rather the first difference were in the 6th significant digit than the 5th.
Joe
Jason G:
--- Quote from: Josef W. Segur on 30 Jun 2011, 01:16:02 am ---AK_v8b_win_SSSE3x.exe has just gotten to bodgy and calculates its score as 1.293091 which is close though I'd rather the first difference were in the 6th significant digit than the 5th.
--- End quote ---
If you are too, I'm content to call this one "remaining chirp annoyances, with added yet to be divined nVidia Gaussfit implementation vagaries"
Jason G:
--- Quote from: Josef W. Segur on 30 Jun 2011, 01:16:02 am --- I don't know how to evaluate the 0.98% difference between bodgy and final scores.
--- End quote ---
Just a naive thought on how that could interact with slight chirp differences: If you take a fairly 'phat' gaussian (wider bandwidth bin leakage or similar effect) then stride it in slightly different angles, you will get a slightly different fit (shape) for very similar (but not the same) peak... could there be some substantial aliasing & could [recommending to the project] some windowed transforms improve that SNR (controlling 'lobing' in the frequency domain)?
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