LabVIEW 2011SP1f1 fails with 32 processor cores

[altenbach]

I got a new system containing two 8 core Xeon E5-2687W workstation chips for a total of 16 cores (32 when counting hyperthreading).

LabVIEW 2011SP1f1 installs fine and opens fine, but as soon as I load anything that uses lvanlys.dll (e.g. AxB.vi from the linear algebra palette), it fails with the following message:

(I include some text here for better forum searching: Invalid access to memory location.)

This is for 32bit LabVIEW. It is even worse with 64bit LabVIEW, where is fails even less gracefully, generating an appcrash instead.

Built applications fail the same way.

After a day of uninstalling, reinstalling, and trying everything imaginable, I found a workaround:

If I limit the number of processors from 32 to 16 in this configuration screen of Windows 7, everything immediately works fine.

It seems that lvanlys.dll in LabVIEW 2011 has an inherent problem with more than 16 processors. I consider this a bug. Hopefully, it is a simple matter of recompiling the dll with better options followed by a new LabVIEW 2011SP1 patch release.

[altenbach]

As a semi-permanent workaround (for now!), I have disabled hyperthreading in the bios, and everything seems to work fine. LabVIEW only sees 16 processors now:

Here's the result from my CPU info program:

Windows 7 Professional Service Pack 1 (build 7601)
Intel(R) Xeon(R) CPU E5-2687W 0 @ 3.10GHz
Intel64 Family 6 Model 45 Stepping 7
# of logical processors = 16
# of packages = 2
# of cores per package = 8
# of logical processors per core = 1
# of Cache Levels = 3, L1=32768, L2=262144, L3=20971520
Physical Memory: 34335174656 Bytes (31.98GB)

[DSPmchen]

Hi Altenbach,

Analysis functions use Intel MKL for better performance.   The MKL version in LabVIEW 2011 SP1 has a bug when the number of cores is more than 16.

Please see the following page for more information.

http://software.intel.com/en-us/articles/intel-mkl-may-stall-on-systems-with-more-than-32-cores/

Thanks,

Michael

[GuenterMueller]

Good point.  Since this issue seems to be fixed since more than one year in the intel MKL: Why is it still in the current version of LabVIEW?

[DSPmchen]

This is because we are not always using latest MKL in LabVIEW.

We are very caustious about upgrading MKL in LabVIEW.   We need to do thorough numerical testing and performance benchmark on various CPU and OS to determine whether or not to upgrade MKL.

[momolxg]

I have a similar machine and am booting in LabVIEW RT.

Looking for a way to increase the number of available cores to 16.

16 cores are found but there is a default limit of 8 cores. Where do I change the default limit?

Thanks

[Norbert_B]

LabVIEW RT has another limitation regarding CPU cores other than LV for Windows. Please contact your local NI branch for further support.

Norbert 

[momolxg]

They have not replied so far 🙂

[kmcdevitt]

Click this url link:  Re: LabVIEW RT does not supports only 8 CPU cores by default. Need More.

[Texas_Diaz]

---

@Norbert_B wrote:

LabVIEW RT has another limitation regarding CPU cores other than LV for Windows. Please contact your local NI branch for further support. 

---

That is correct.  It has to do with our scheduler on RT, it doesn't always do well when you go above 8 cores.  Depending on the CPU architecture we can go up to 16 cores with ease, or the scheduler may crash horrifically at 12 cores.  Contacting NI and getting us to help you attempt this feat adds with it the "no lifeguard on duty" and "we're not supporting this, so beware" waivers.  

-Danny