mersenneforum.org mfaktc: a CUDA program for Mersenne prefactoring
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 2016-11-18, 06:01 #2685 storm5510 Random Account     Aug 2009 U.S.A. 32×11×17 Posts A simple question: Does mfaktc read the entire worktodo file into a queue, or does it take it one line at a time?
 2016-11-18, 06:49 #2686 James Heinrich     "James Heinrich" May 2004 ex-Northern Ontario 23×397 Posts Pretty sure it reads line by line, skipping any invalid lines, until it finds a valid assignment. Once it has finished the assignment it rewrites the entire worktodo, minus the assignment-line it just completed. Side note: disk I/O can be killer (e.g. 1-10MB/s sustained) for things like TF>1G where an assignment is completed every second or so and a large input buffer is maintained -- a RAM drive is essential.
2016-11-18, 16:23   #2687
storm5510
Random Account

Aug 2009
U.S.A.

32×11×17 Posts

Quote:
 Originally Posted by James Heinrich Pretty sure it reads line by line, skipping any invalid lines, until it finds a valid assignment. Once it has finished the assignment it rewrites the entire worktodo, minus the assignment-line it just completed. Side note: disk I/O can be killer (e.g. 1-10MB/s sustained) for things like TF>1G where an assignment is completed every second or so and a large input buffer is maintained -- a RAM drive is essential.
It reads it into a buffer, like I suspected. I've noticed that when it has a larger bit range, for example 272 to 274, it will write the intermediate stage when complete. This explains the add file feature. I have been stopping it to add assignments to the worktodo file.

TF>1G: I suspected there were people out there doing this but I had no idea of the magnitude of it. A very interesting page; I bookmarked it.

 2016-11-26, 19:25 #2688 cseizert     "Curtis" Sep 2016 Fort Collins, CO 2×5 Posts I think there would be a speedup for Pascal cards if the linux version were compiled with 8.0. Actually, I cannot run the current binaries unless I change the makefile and compile them for compute 6.1. But even if you can get this to run on a Pascal card in its current form, my experience suggests that there is a performance penalty for running binaries compiled for compute capability <6.0 cards on the 1080 or 1070.
 2017-01-14, 23:29 #2689 Xyzzy     "Mike" Aug 2002 22×1,951 Posts We've had a (FE) GTX 1060 card for several months but never got around to running mfaktc. We tried it today and it just worked, out of the box, without anything extra needed! In the past we had to install the CUDA toolkit but we didn't today. The card is doing roughly 530 GHz-d/day and the display has no lag whatsoever. The card is at 80 C and it is nearly silent. We didn't modify the fan curve or anything.
 2017-01-15, 04:54 #2690 kladner     "Kieren" Jul 2011 In My Own Galaxy! 3×17×197 Posts Do you have fan headroom to bring that down a bit from 80? I get nervous in the upper 70s.
 2017-03-10, 03:02 #2691 planetclown   Feb 2012 5 Posts Are there updated linux64 binaries available for cuda 8? I don't see them in the download section or in this thread. If not, how difficult would it be to compile them? I recently upgraded from a 970 to 1070 and am getting the 'cudaGetLastError() returned 8: invalid device function' error. Thank you!
2017-03-10, 16:29   #2692
planetclown

Feb 2012

5 Posts

I took a stab at compiling the linux64 binaries myself using the cuda8 toolkit and it's running successfully. The GHz-d/day is hovering around 780 in the terminal for my GTX 1070, and nvidia-smi shows GPU utilization in the high 90's.

When compiling I added an nvcc flag for compute 6.1 capabilities. I also had to remove the existing line for compute 1.1 (Tesla?) since it wouldn't compile with that flag. Otherwise I left all settings the same as in the source file for mfaktc with cuda 6.5.

I copied the compiled mfaktc.exe and the libraries for cuda 8.0.61 on top of the existing folder structure for mfaktc with cuda 6.5. Attached is the result if anyone else is looking for or wants to test it.

Be aware I'm not an expert, so use at your own risk.
Attached Files
 mfaktc-0.21.linux64.cuda80.tar.gz (1.38 MB, 62 views)

 2017-03-10, 18:30 #2693 flashjh     "Jerry" Nov 2011 Vancouver, WA 1,123 Posts Thank you
2017-03-12, 15:27   #2694
bayanne

"Tony Gott"
Aug 2002
Yell, Shetland, UK

313 Posts

Quote:
 Originally Posted by planetclown I took a stab at compiling the linux64 binaries myself using the cuda8 toolkit and it's running successfully. The GHz-d/day is hovering around 780 in the terminal for my GTX 1070, and nvidia-smi shows GPU utilization in the high 90's. When compiling I added an nvcc flag for compute 6.1 capabilities. I also had to remove the existing line for compute 1.1 (Tesla?) since it wouldn't compile with that flag. Otherwise I left all settings the same as in the source file for mfaktc with cuda 6.5. I copied the compiled mfaktc.exe and the libraries for cuda 8.0.61 on top of the existing folder structure for mfaktc with cuda 6.5. Attached is the result if anyone else is looking for or wants to test it. Be aware I'm not an expert, so use at your own risk.
Hmm, I wonder whether that would run on a Mac, which I have running another GPU project on cuda 8.0.53 ...

 2017-03-23, 22:49 #2695 TheJudger     "Oliver" Mar 2005 Germany 21268 Posts stock 1080 Ti "Founders Edition" Code: # ./mfaktc.exe -tf 66362159 75 76 mfaktc v0.21 (64bit built) [...] CUDA device info name Graphics Device compute capability 6.1 max threads per block 1024 max shared memory per MP 98304 byte number of multiprocessors 28 clock rate (CUDA cores) 1582MHz memory clock rate: 5505MHz memory bus width: 352 bit [...] Date Time | class Pct | time ETA | GHz-d/day Sieve Wait Mar 23 23:43 | 0 0.1% | 7.003 1h51m | 1481.90 82485 n.a.% Mar 23 23:44 | 4 0.2% | 6.980 1h51m | 1486.78 82485 n.a.% Mar 23 23:44 | 9 0.3% | 7.003 1h51m | 1481.90 82485 n.a.% Mar 23 23:44 | 12 0.4% | 7.110 1h53m | 1459.59 82485 n.a.% Mar 23 23:44 | 16 0.5% | 7.494 1h59m | 1384.80 82485 n.a.% Mar 23 23:44 | 24 0.6% | 7.928 2h06m | 1309.00 82485 n.a.% Mar 23 23:44 | 25 0.7% | 7.955 2h06m | 1304.55 82485 n.a.% First 20-25 seconds: limited by power target (250W) After 20-25 seconds: limited by thermal target, hovers around at ~190W. Reason need more fresh air in chassis. Oliver Last fiddled with by TheJudger on 2017-03-23 at 22:53

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