mfaktc: a CUDA program for Mersenne prefactoring - Page 205

kracker · 2013-03-23, 02:19

I believe mfaktc has very little gpu memory usage. CuLu, however does of course.

Dubslow · 2013-03-23, 03:02

Quote:

Originally Posted by kracker

I believe mfaktc has very little gpu memory usage. CuLu, however does of course.

Quite. If you're running only mfaktc, memory clock will have little to no impact on performance. If you run CuLu, memory clock should scale mostly linearly with performance (up to some upper limit that's probably out of reach -- be sure your card is absolutely stable with at least a few double checks).

Chuck · 2013-03-23, 12:33

Quote:

Originally Posted by Xyzzy

We have been messing around with the extremely confusing "EVGA Precision X" software. There are so many options it is ridiculous!

Anyways, we were messing with the memory clock setting. By default on our GTX690 it is 1502.3MHz. We lowered this to 1252.8MHz and the performance did not change!

The temperatures and voltages do not change, either.

Does this make sense?

Would running the memory slower like that make it less likely to have a flipped bit?

FWIW, the GPU clock is 1058.2MHz. The performance changes a lot when we mess around with that!

I had my memory clock cranked way down on the 580 and it made no noticeable change on the performance or temperature.

Redarm · 2013-04-04, 15:15

running MF , the performance should scale linear with GPU-clock

gpu clock * gpufactor = Ghz-d/Day

ex.

966mhz *x = 439
x = 0,454

1241mhz * 0,454 = ?

*proven*

Mini-Geek · 2013-04-14, 12:38

Is there any way to disable the "simple selftest" on startup? Maybe just run it once for each version of mfaktc or once per month? It wastes time that it could spend crunching when you switch stop and start it often, e.g. to switch speeds.

TheJudger · 2013-04-14, 15:15

Without changing some code and recompile or binary hacking: no, not possible.
And there is (at least) one broken driver version available in the wild so I don't recommend to do so. How much time does it really take on your system?

Oliver

Mini-Geek · 2013-04-15, 01:26

Quote:

Originally Posted by TheJudger

Without changing some code and recompile or binary hacking: no, not possible.
And there is (at least) one broken driver version available in the wild so I don't recommend to do so. How much time does it really take on your system?

Oliver

About 6-7 seconds. It seems longer when using my controller app because it doesn't show the output until mfaktc finishes the first class (first time it senses a newline, I suppose) which means it looks like closer to 18 seconds on my current GPU/assignment.
I was under the impression that it really only was meant to test mfaktc's internals, but the fact that it can detect a broken driver makes it more useful.
I guess it's really not as bad as I thought, all things considered. I wouldn't expect most people to spend more than about a minute (~10 runs) per day running the selftest, really a trivial amount.
Thanks for the info.

Aramis Wyler · 2013-04-15, 04:53

Odd, I don't run that selftest more than once every few days. Do you turn the program off and on a lot?

Mini-Geek · 2013-04-15, 13:15

Quote:

Originally Posted by Aramis Wyler

Odd, I don't run that selftest more than once every few days. Do you turn the program off and on a lot?

Yes, as part of switching speeds using my MfaktX Controller tool. Mfaktc doesn't support a nicer way of switching the GPUSieveSize, so the tool stops mfaktc, changes the ini file, and then starts it again. Due to the selftest, there's a few seconds of lost time each time you do this. I have the tool set up to switch automatically when the screensaver goes off or on, and there's a PauseWhileRunning feature, and you can change it any time you want, so it can happen a number of times per day - but at 6-7 seconds per, it's not a significant loss.

c10ck3r · 2013-04-24, 22:20

Okay, I have questions that have probably been asked time and time again: what is the minimum exponent that can be tested with mfaktc 0.20? What is the minimum bit depth? Maximum? Is there a maximum exponent testable by design, or just based on memory?
Thanks in advance!

firejuggler · 2013-04-24, 22:29

If memory serve, smallest expo is 1M, maximum 2^32-1 (or was it 2^31-1?), following that, minimum depth should be 20, and maximum... well.. 2^31-1?

2013-04-04, 15:15	#2248
Redarm Apr 2012 Berlin Germany 3·17 Posts	running MF , the performance should scale linear with GPU-clock gpu clock * gpufactor = Ghz-d/Day ex. 966mhz x = 439 x = 0,454 1241mhz 0,454 = ? proven Attached Thumbnails Last fiddled with by Redarm on 2013-04-04 at 15:22

2013-04-14, 12:38	#2249
Mini-Geek Account Deleted "Tim Sorbera" Aug 2006 San Antonio, TX USA 10AB₁₆ Posts	Is there any way to disable the "simple selftest" on startup? Maybe just run it once for each version of mfaktc or once per month? It wastes time that it could spend crunching when you switch stop and start it often, e.g. to switch speeds. Last fiddled with by Mini-Geek on 2013-04-14 at 12:39

2013-04-24, 22:29	#2255
firejuggler Apr 2010 Over the rainbow 5056₈ Posts	If memory serve, smallest expo is 1M, maximum 2^32-1 (or was it 2^31-1?), following that, minimum depth should be 20, and maximum... well.. 2^31-1? Last fiddled with by firejuggler on 2013-04-24 at 22:30

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2013-03-23, 02:19	#2245
kracker "Mr. Meeseeks" Jan 2012 California, USA 2³·271 Posts	I believe mfaktc has very little gpu memory usage. CuLu, however does of course.

2013-04-14, 15:15	#2250
TheJudger "Oliver" Mar 2005 Germany 2127₈ Posts	Without changing some code and recompile or binary hacking: no, not possible. And there is (at least) one broken driver version available in the wild so I don't recommend to do so. How much time does it really take on your system? Oliver

2013-04-15, 04:53	#2252
Aramis Wyler "Bill Staffen" Jan 2013 Pittsburgh, PA, USA 424₁₀ Posts	Odd, I don't run that selftest more than once every few days. Do you turn the program off and on a lot?

2013-04-24, 22:20	#2254
c10ck3r Aug 2010 Kansas 1043₈ Posts	Okay, I have questions that have probably been asked time and time again: what is the minimum exponent that can be tested with mfaktc 0.20? What is the minimum bit depth? Maximum? Is there a maximum exponent testable by design, or just based on memory? Thanks in advance!