mfaktc: a CUDA program for Mersenne prefactoring

[TheJudger]

Originally Posted by LaurV

@Oliver: small cosmetic for 0.19 less classes version (I only tested win64): it still displays 4620 classes (like 0/4620, 1/4620 .... 419/4620). better check that compiler option against hard coded screen messages Otherwise, it seems to work wonderfully well.

Well, you can adjust this in mfaktc.ini, it is a runtime option. But you're right, I should have adjusted this in the default config.

Oliver

[TheJudger]

Are they real world situations where a single core of a CPU can't feed a single CC 1.x GPU (running mfaktc, ofcourse)?

Oliver

P.S. I'm not talking about a theoretical rig with a crappy Netburst P4 on low clocks driving a Hyperclocked GTX 285 running very low exponents.

[James Heinrich]

Originally Posted by TheJudger

Are they real world situations where a single core of a CPU can't feed a single CC 1.x GPU (running mfaktc, ofcourse)?

I guess I live where real world meets theory: I'm playing with small TF on large exponents (2⁶⁴ on >1000M) and mfaktc thrashes madly to try and keep up.

On 8800GT (CC 1.1) with i7-920 @3.2GHz, two mfaktc instances get 98% GPU usage, but at SP=2000 and "wait" value of about 55.

On GTX 570 (CC 2.0) on i7-3930K @ 4.2GHz it's a similar story in this range, it takes 3 instances at SP=2000 to get up to 96% GPU usage, but overall throughput is better with 6 instances.

Both examples running v0.19-lessclasses; Grid=0 on the 8800GT and Grid=3 on the GTX 570.

And yes, I know this doesn't really qualify as "real world" usage, but since you asked...

[lalera]

the performance of my machine
sbe 3930k at 3.5ghz with a gtx580 at 810mhz
mfaktc v0.19 lessclasses
default-mfaktc.ini
exponents about 865400000
bit 65 to 66
6 instances
about 13 seconds per candidate
gpu at 98%

[lalera]

the performance of
q6600 with gtx260
one instance
--
0.19
Factor=N/A,370000123,65,66
45m/sec
1:20min
gpu 64%
--
0.19 lessclasses
Factor=N/A,370000123,65,66
59m/sec
45 sec
gpu 88%
--

[Prime95]

I think the time may have come to no longer worry much about optimizing mfaktc for CC 1.X GPUs.

[frmky]

Originally Posted by Prime95

I think the time may have come to no longer worry much about optimizing mfaktc for CC 1.X GPUs.

My poor S1070.

[ixfd64]

Originally Posted by Prime95

I think the time may have come to no longer worry much about optimizing mfaktc for CC 1.X GPUs.

I'm guessing it won't be long now until the code is integrated into Prime95?

[Prime95]

Originally Posted by ixfd64

I'm guessing it won't be long now until the code is integrated into Prime95?

I have no intention of doing that. I had thought about defining a plug-in interface for programs like mfaktc, but I've been sidetracked doing other work.

[ixfd64]

So does this mean Prime95 won't have built-in GPU code in the short term?

[Dubslow]

Originally Posted by ixfd64

So does this mean Prime95 won't have built-in GPU code in the short term?

The problem really is independent development. It's impractical to release a new Prime95 every time TheJudger or Bdot release a new mfakt* version. That would be the idea of a plug-in interface, but such a thing is decidedly non-trivial.