mfaktc: a CUDA program for Mersenne prefactoring

[James Heinrich]

Originally Posted by bcp19

Running the 32 bit program by itself on core 4

Is there any reason to lock v0.20 to any particular core? What if you let it run on whichever core it chooses, do you still get the wild variance?

[bcp19]

Originally Posted by James Heinrich

Is there any reason to lock v0.20 to any particular core? What if you let it run on whichever core it chooses, do you still get the wild variance?

Holdover from the old days of .19 and below. I know the Quad is very finicky when pushed too far with P95... with core 1/3 running DC/LL I can do x DC/LL every y days, but if I saturate the computer with 4 dc/ll, I only get 1.5x in the same y days. I will try to remember to check your suggestion when I am at that system tomorrow.

[Xyzzy]

Do all video cards, when used for the primary/secondary display, lag severely when gpu sieving is enabled?

[Dubslow]

Originally Posted by Xyzzy

Do all video cards, when used for the primary/secondary display, lag severely when gpu sieving is enabled?

Mine does, that's for sure. I only run mfaktc (or Msieve) when I'm not using ut.

[ixfd64]

Mine is a GTX 555, and it lags as well.

[Xyzzy]

It would be convenient to be able to click a button and pause activity, and maybe have the activity resume automatically in an hour. Or maybe have mfaktc run at a lower priority or do a "PauseWhileRunning" deal.

Is this something that could be easily coded?

We have no problem stopping the program but we frequently forget to restart it.

We are currently running on a GT 430 but we have a GTX 660Ti to install tomorrow.

[James Heinrich]

Originally Posted by Xyzzy

we have a GTX 660Ti to install tomorrow.

A benchmark would be appreciated.

[Prime95]

Originally Posted by Xyzzy

Do all video cards, when used for the primary/secondary display, lag severely when gpu sieving is enabled?

Knock down the GPUSieveSize parameter until you get acceptable video response time.

[Xyzzy]

Knock down the GPUSieveSize parameter until you get acceptable video response time.

We changed "GPUSieveSize" from the default 32 to 4 (!) and the system is much more responsive now. On the GT 430 the estimated GHz-d/day dropped from ~50 to ~45 but we figure letting it run most of the time, rather than on and off and on and off, it might have better throughput. (The GHz-d/day is also much more variable per output line, possibly because the GPU is being allowed to do other work?)

By setting "GPUSieveSize" to the lowest value are we messing anything up, or do we need to balance any other settings?

[kracker]

I would be curious as to how much a 660 Ti spits out too

[Dubslow]

Originally Posted by Prime95

Knock down the GPUSieveSize parameter until you get acceptable video response time.

(560) I had reduced mine from 64 to 16, but that wasn't really good enough; throughput went from ~215 to ~205; I'm running it with 4 now, and the lag is acceptable, but throughput has dropped to ~185, but I suppose Xyzzy's logic still applies.