mfaktc: a CUDA program for Mersenne prefactoring

[Christenson]

Originally Posted by Dubslow

Two questions: is there any work to getting mfaktc CPU independent?

And two, more complicated: I have 4 cores, 8 threads. I have 3 P95 workers running on two threads apiece, occupying logical CPU's 3-8. I had the last worker running only on logical CPU 1, leaving 2 empty for mfaktc. When I started mfaktc, it started taking cycles from all of the other CPU's, affecting their performance and not making use of logical thread 2. Is there anyway to set mfaktc onto one particular core/thread?

Right now, making mfaktc more CPU-independent by doing sieving on the card is on my wish list. It's taking me longer than I would like to make mfaktc talk to primenet, so I'll be happy if someone comes along and scoops me (does the job first). Oliver might do the job, too, so check with him.

Second, from the standpoint of either Windows or Linux, mfaktc is "just a program", not really using threads. If you want to lock it to a particular CPU core, ask your OS to do that. If you want to set its priority, ask your OS to do that. I think it's part of task manager in Windows.

Oh, and I'm pretty sure that it is not effective to try to use more logical cores than you have physical cores -- you just waste less time in context switching than if you ran twice as many threads as you had CPU -- but you still pay for the context switches.

[James Heinrich]

Originally Posted by Christenson

If you want to lock it to a particular CPU core, ask your OS to do that. If you want to set its priority, ask your OS to do that. I think it's part of task manager in Windows.

It is. Processes tab, right-click on mfaktc.exe and choose either "Set Priority" or "Set Affinity..." as appropriate.

[ET_]

Originally Posted by frmky

You can use CUDA 4.0 on your GTX 275, you just can't take advantage of the fancy new features that require CC 2.x. I'm stuck in the same boat with the Tesla S1070.

But yes, the 4.0 driver will run code compiled with 3.x.

Thank you very much!

Luigi

[MrHappy]

What does "avg. wait" mean? I get values from ca. 100 to ca. 3000 alternating... and 60M/s on my GT555M.

[Brain]

Originally Posted by MrHappy

What does "avg. wait" mean? I get values from ca. 100 to ca. 3000 alternating... and 60M/s on my GT555M.

CPU average waiting time for GPU "hunger" (sieving part done in CPU). Values < 100 indicate process is CPU limited, values > 1000 indicate GPU being saturated.

[xilman]

Originally Posted by xilman

Miserable failure here

Success.

The 280 series driver turned up and installed fine. Most of the SDK built and run once the gcc version check had been disabled. The only thing missing are the graphical demos and that only because I haven't installed the GL libraries yet.

Thanks, everyone, for your help and/or encouragement.

Paul

[Dubslow]

Originally Posted by James Heinrich

It is. Processes tab, right-click on mfaktc.exe and choose either "Set Priority" or "Set Affinity..." as appropriate.

Thanks, I'll give it a shot next time I'm in Windows. Now, on to the next problem: I can't compile the source in Linux, as detailed above; it doesn't support my newer GCC version. I removed the line that checks the GCC version, and then it compiled, but didn't run anyways. Can somebody zip up a working Linux64 executable for me? (Or anybody else either having compiling problems or not technical enough to try.)

[TheJudger]

Hi!

Originally Posted by Dubslow

Now, on to the next problem: I can't compile the source in Linux, as detailed above; it doesn't support my newer GCC version. I removed the line that checks the GCC version, and then it compiled, but didn't run anyways. Can somebody zip up a working Linux64 executable for me? (Or anybody else either having compiling problems or not technical enough to try.)

can you describe the problem? "didn't run anyways" doesn't help.
I uncommented the version check once on a openSUSE 11.4 with CUDA 4.0 and it seems to work fine for mfaktc.
Anyway I'll try to provide a Linux64 binary later.

Oliver

[TheJudger]

Hi,

you can find a Linux x86-64 binary here: http://www.mersenneforum.org/mfaktc/...linux64.tar.gz
let me know if this works. If it tells you that it can't find libcudart.so.3 you can try to run 'LD_LIBRARY_PATH=./lib ./mfaktc.exe'.

Oliver

[Dubslow]

Cool, thanks. Do you have any idea how to get one worker thread to stop in Linux? It was in the GUI in Windows, but I can't find it anywhere in the -m menu.

[Dubslow]

Hmm. It runs fine except that it throws errors reading the worktodo.txt file. I'm using the same file as in Windows, and it has the right number of lines, so I know it's reading the same file, but I can't tell why it won't work. The file looks just fine in gedit. It says WARNING: ignoring line () Reason: invalid data