3D parametric surface CPU load

[RExler]

As soon as I put a 3D parametric surface graph on my front panel of a VI CPU load increases to 50% on a Pentium Dual 3GHz machine. This means in average one core of the CPU is locked completely. CPU load decreases to normal level only after LabVIEW is closed completely. Closing the VI is not enough.  The same is true of you just open the attached VI (run windows task manager to view the performance graph before).

Hardware:

Operating System	Microsoft Windows XP Professional Service Pack 2 (5.01.2600)
Processor	Intel(R) Pentium(R) D CPU 3.00GHz / x86 Family 15 Model 4 Stepping 7 / GenuineIntel / 2992 MHz
Memory	1,022 MB RAM
Disk Space	C:\ 18,148 of 40,962 MB free D:\ 1,278 of 111,968 MB free E:\ 4,645 of 9,552 MB free

Software LabVIEW Version 8.20 (Professional / Devoper Suite)

As long as no other Programs have high CPU load this is normally not recogniced by the user. But if you start for example another executeable which uses a 3D parametric surface too user interfaces slow down significantly.

What's going on here and how can this be avoided?

   Roland

[altenbach]

Please try once more to attach your VI. It did not make it. 😉

[RExler]

I've just noticed the same and try again.

In between I've one more information: Running the same on an old LabVIEW 6.1 system (Pentium M 850 MHz/384MBytes of RAM) doesn't show excessive CPU load, just if you operate the 3D plot (rotate it).

Even more interesting: The same is true for another PC running LV8.2. The difference between the two systems is that the one with the performance problems had 8.0 installed and updated later, the second one has been set up the first time with 8.2. I'll investigate this in more detail.

Roland

[RExler]

I did a mass compile of all the VI's in the NI/LabVIEW folder in between. The only thing which has changed is that LabVIEW no longer complains about sub-VI's recompiled / save? if I close the VI using the 3D control now. The CPU load problem remains unchanged.

Maybe I'll uninstall all NI software, clean the registry and resinstall tomorrow.

Roland

[RExler]

I traced the problem down using a process explorer - a tool similar to task manager but able to show all dll's a program is using and the time it spends within it. Using this I found the high CPU load to be in C:\WINDOWS\nvoglnt.dll. Windows Task manager just displays all the time a program uses up under it's

This is the Open GL driver coming with the NVIDIA Geforce graphics card. Updating the graphic driver (download from nvidia.com) solved the problem.

PS: In between I had found another application showing the same problem. This helped to trace the problem.