Prime95 for core2duo under Win32?

[ewmayer]

I sent e-mail about this issue to George yesterday, but from his note in one of the forums for earlier today I see he's just gone on vacation, so I'll post it here in hopes that our knowledgeable readers will be able to help.

Is there a multithreaded version of Prime95 for Intel x64 core2duo under 32-bit Win? (WinXP, specifically.) If so, how is the 2-cpu performance [and should I run 2 or 4-thread to maximize that] vs running one copy per CPU [and again, is it best to use 1 thread or 2 per CPU].

Thanks,
-Ernst

[Mini-Geek]

Originally Posted by ewmayer

I sent e-mail about this issue to George yesterday, but from his note in one of the forums for earlier today I see he's just gone on vacation, so I'll post it here in hopes that our knowledgeable readers will be able to help.

Is there a multithreaded version of Prime95 for Intel x64 core2duo under 32-bit Win? (WinXP, specifically.) If so, how is the 2-cpu performance [and should I run 2 or 4-thread to maximize that] vs running one copy per CPU [and again, is it best to use 1 thread or 2 per CPU].

Thanks,
-Ernst

Prime95 25.4 is multithreaded.
http://www.mersenneforum.org/showthread.php?t=8981
Specifically, the Windows 32-bit version:
ftp://mersenne.org/gimps/p95v254.zip
I can't seem to find exact numbers on how the 2-cpu performance is, but I know that it's not 100% efficient (90% comes to mind, but I'm not sure), and you'd get the most out of your CPU by running two separate threads on two separate cores/CPUs.

[JCoveiro]

I have a quad-core 4 cores 4 threads
should I use 25.5 x64 instead of 24.14 x64 for each cpu?
I see that the threads boost a little in my qx6700 and even
in my core 2 duo laptop. ??

[mdettweiler]

Originally Posted by JCoveiro

I have a quad-core 4 cores 4 threads
should I use 25.5 x64 instead of 24.14 x64 for each cpu?
I see that the threads boost a little in my qx6700 and even
in my core 2 duo laptop. ??

Running 25.5 with 4 different threads should be equivalent performance-wise to running 4 separate instances of 24.14 simultaneously (unless 25.5 has other kinds of performance improvements that I haven't heard of).

[jasong]

Originally Posted by Anonymous

Running 25.5 with 4 different threads should be equivalent performance-wise to running 4 separate instances of 24.14 simultaneously (unless 25.5 has other kinds of performance improvements that I haven't heard of).

I don't know if this is what you mean by 'performance improvements', but you can run an LLR test on more than one core. My personal favorite is running a test on either the first or last two cores. It takes about 53% of the time it normally would, so you're only losing about 6% efficiency. Which may be a good thing if the 10M digit prime is close by.

[mdettweiler]

Originally Posted by jasong

I don't know if this is what you mean by 'performance improvements', but you can run an LLR test on more than one core. My personal favorite is running a test on either the first or last two cores. It takes about 53% of the time it normally would, so you're only losing about 6% efficiency. Which may be a good thing if the 10M digit prime is close by.

No, I didn't mean that; what I meant was that I didn't know of any performance improvements in 25.5, just that if there happened to be any, that might throw off my statement about 4 instances of 24.14 equaling 25.5 with 4 threads.

[spubads]

Originally Posted by Mini-Geek

Prime95 25.4 is multithreaded.
http://www.mersenneforum.org/showthread.php?t=8981
Specifically, the Windows 32-bit version:
ftp://mersenne.org/gimps/p95v254.zip
I can't seem to find exact numbers on how the 2-cpu performance is, but I know that it's not 100% efficient (90% comes to mind, but I'm not sure), and you'd get the most out of your CPU by running two separate threads on two separate cores/CPUs.

*-*-*-*-*-*

I could not download ftp://mersenne.org/gimps/p95v254.zip, it looks like that it is missing at the source. Can you email or post the validated link for the file. I need to use the same to test Q6600 C2Q processor. Thanks.

[Xyzzy]

http://www.mersenneforum.org/showthread.php?t=9779

[spubads]

Thanks a lot for the link.