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Old 2011-11-07, 23:02   #23
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Default mfakto update, please

Dubslow mentioned I might want to comment on the mfakto-part of the pdf ... sorry I did not take part in that earlier.

And indeed, the "DO NOT SUBMIT “NO FACTOR” RESULTS YET" statement is a bit outdated. Apart from the bug with version 0.08 that may lead to missed factors < 248, there's no known reason for not reporting all results.

Regarding the Factor size: There is no lower limit for the factors, so for mfaktc this should just read "Factor size <= 295 ". mfakto does not yet have the 95-bit kernel, so for mfakto the limit is "Factor size <= 292 ".

As an estimated GIMPS score you can use (maybe I should test that some day):

roughly 60 GHz days/day on HD5770 & 2 CPU cores

This is also a bit misleading: "mfakto works best on large exponents as the sieving (CPU) part stays constant with larger numbers."
mfakto (and mfaktc) are more efficient with larger assignments. This does not mean larger exponents, but "more work" or "longer runtime per class", generally bigger bit ranges. The reason is a certain one-time initialization effort per class - no matter if the class will just test 1 million factor candidates or 1 billion. In the first case, the one-time effort may account for, say, 75% of the sieving effort, in the latter case just 0.3%. Plus there is an average of half a block wasted for each class. If the class consists of only one block, that's 50%, for 1000 blocks it's just 0.05%.

Last fiddled with by Bdot on 2011-11-07 at 23:41 Reason: large exponents vs. large assignments
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Old 2011-11-08, 06:10   #24
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I'm going to integrate this information asap.
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Old 2011-11-08, 07:14   #25
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Quote:
Originally Posted by Brain View Post
I'm going to integrate this information asap.
You may want to add about the mini-pirmenet that Chasall has set up to aid the factoring to extra bit depths ahead of the LL 'wave front'.
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Old 2011-11-08, 08:39   #26
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Quote:
Originally Posted by Bdot View Post

As an estimated GIMPS score you can use (maybe I should test that some day):

roughly 60 GHz days/day on HD5770 & 2 CPU cores
I just checked the crunching-power of my HD5770-box. The last 24 hrs returned 96.6 GHz-days, using 3 CPU-cores. So I guess mentioning 90 GHz-days/day with 2 cores should be quite safe.
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Old 2011-11-08, 21:26   #27
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Post GPU Computing Guide Update to v 0.06

This is a replacement for 0.05a. Please review.

Several minor changes:
  • mfakto: All results submittable
  • mfakto: Decreased upper factor size limit
  • GPU to 72 tool
  • ATI driver warning for 11.10
  • ATI: GIMPS score estimate added
  • CUDALucas: Unknown upper limit
  • Call for P-1 and ECM implementations
GIMPS GPU Computing Cheat Sheet (pdf)

Last fiddled with by Brain on 2012-08-05 at 10:15
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Old 2011-11-09, 04:31   #28
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Quote:
Originally Posted by Brain View Post
P.S.: We still need somebody to implement the following work types on a GPU:
-- P-1 factoring
-- ECM factoring
Code it and enter the GIMPS hall of fame…
How about CudaNFS, CudaQS/SIQS/MPQS (at least for init phase)?
Will it have some effect on the speed(time)? etc.
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Old 2011-11-12, 11:42   #29
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Quote:
Originally Posted by LaurV View Post
How about CudaNFS, CudaQS/SIQS/MPQS (at least for init phase)?
Will it have some effect on the speed(time)? etc.
Undoubtedly possible, but doubtedly worth the effort for NFS. Assuming, that is, you want the sieving phase to be implemented in CUDA. Polynomial selection is already available in msieve. Filtering is too I/O intensive to make sense to port to CUDA and I don't yet have a good enough feel for the square root phase to make sensible comments.

As a rule, GPUs are good at computation, poor at memory access and lousy at I/O compared with CPUs. The sieving phase is very heavily memory bound ...


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Old 2011-11-13, 06:17   #30
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Thanks for the answer, it was more like a curiosity, my understanding of NFS is almost zero at this time.
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Old 2011-11-13, 06:26   #31
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Quote:
Originally Posted by Brain View Post
This is a replacement for 0.05a. Please review.

Several minor changes:
  • mfakto: All results submittable
  • mfakto: Decreased upper factor size limit
  • GPU to 72 tool
  • ATI driver warning for 11.10
  • ATI: GIMPS score estimate added
  • CUDALucas: Unknown upper limit
  • Call for P-1 and ECM implementations
garo...
or some other mod...
(and the other FAQ thread as well)
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Old 2012-01-11, 22:05   #32
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Looking for an old post, found that this PDF is still v.06, while the other FAQ has v.07.
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Old 2012-01-13, 09:27   #33
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BTW, mfakto 0.10 / 0.10p1 solved the issues with the latest Catalyst drivers. 11.10 to 11.12 are tested well.
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