Prime95 version 29.4

[VBCurtis]

Originally Posted by theonetruepath

Heh of course you can't. So I took an arbitrary time period and worked out how many iterations each worker contributed in that time, then worked out net msecs per iter for the system
13 cores is 1.62 ms/iter
10 cores is 1.42 ms/iter

Maybe the program could work this out from time to time...

It does. Consider it a homework assignment to find the benchmark tools, run such a benchmark, and choose whichever combination of workers and threads per worker maximizes iterations per second.
It may be that the first time you ran it, you had something else running that confused the testing process and left P95 with that 13-core choice.

[theonetruepath]

Originally Posted by VBCurtis

It does. Consider it a homework assignment to find the benchmark tools, run such a benchmark, and choose whichever combination of workers and threads per worker maximizes iterations per second.
It may be that the first time you ran it, you had something else running that confused the testing process and left P95 with that 13-core choice.

I had a few tiling programs flogging 4 threads yes.

So apparently 1 worker with 10 cores is quickest...

Down to 1.28 ms/iter now

[Prime95]

Originally Posted by theonetruepath

Any idea why version 29.5 crashes on my system - is there some diagnostic info I can scrape together for you?

See https://www.mersenneforum.org/showpo...0&postcount=99

[theonetruepath]

Originally Posted by Prime95

See https://www.mersenneforum.org/showpo...0&postcount=99

Yup I tried that one as well. Both versions ask the initial questions if firing up in a 'clean' directory, but crash immediately when finished with those, and immediately if running subsequently but without those initial questions.

[Prime95]

Originally Posted by theonetruepath

Yup I tried that one as well. Both versions ask the initial questions if firing up in a 'clean' directory, but crash immediately when finished with those, and immediately if running subsequently but without those initial questions.

If you add "CPUSupportsAVX512F=0" to local.txt, does it still crash?

[theonetruepath]

Originally Posted by Prime95

If you add "CPUSupportsAVX512F=0" to local.txt, does it still crash?

That stops it crashing. Seems to run slower than the older version though.

[Prime95]

Originally Posted by theonetruepath

That stops it crashing. Seems to run slower than the older version though.

That should make it essentially equivalent to 29.4. The question is why does your machine crash trying to use AVX-512 instructions.

[theonetruepath]

Originally Posted by Prime95

That should make it essentially equivalent to 29.4. The question is why does your machine crash trying to use AVX-512 instructions.

Might be something to do with this. (I'm running Windows 7 Pro)
============================
Note that an operating system (OS) needs to support the new extended CPU state (OS-XSAVE) to allow software to use new instruction sets like AVX, AVX2/FMA, AVX512*, etc.

Windows 7, 8.x, 10.x or later / Server 2008/R2, 2012/R2, 2016 is required.

* AVX512 and later are/will only supported by Windows 10.x / Server 2016.

Older operating systems like Windows XP, Windows Vista and earlier have not been updated and are not likely to be.

[theonetruepath]

Here is what y-cruncher says:
======================
Performance Warning:

This processor supports AVX512 instructions. However, it cannot be used
because the operating system has not enabled it.

This could be due to either of the following reasons:
- The operating system is too old and does not support AVX512.
- AVX512 has been explicitly disabled.

To achieve maximum performance, AVX512 must be enabled in the OS.
======================
So I'm hoping Microsoft will come to the party with a hotfix to enable AVX-512 in Windows 7...

[retina]

Yeah. I think P95 could be improved by testing that the instructions can be executed, instead of assuming they can be executed by only reading the feature bits. Indeed there is no need to read the feature bits at all, just test the instructions and catch any exceptions. That way you test the entire path: CPU, OS, VM, etc.; all the things that might not have support for recent instructions.

[Prime95]

Originally Posted by retina

Yeah. I think P95 could be improved by testing that the instructions can be executed, instead of assuming they can be executed by only reading the feature bits. .

Will do