While loop speed depends on size of screen displayed

[Ledge]

I am running a relatively straightforward VI which has a single While loop. Labview Version is 8.6, OS is Windows XP. The machine I am running on is very fast, with two quad-core processors.

I am displaying around 30 parameters on the front panel. The loop rate is set at 20ms, but the best loop speed I can get is around 200-250ms, which is unbelievably slow. However, if I tile the front panel (so fewer gauges are showing), the loop speed increases significantly. And as I drag the tiled front panel to a smaller and smaller size, the loop speed gets faster and faster.  

A look at the CPU performance while the VI is running indicates that one core is maxed out, while the other seven are doing next to nothing. If I set two VIs running simultaneoulsy, one core is still doing all the work.

Is this a graphics card problem, an OS problem or a LabVIEW problem?

[AdnanZ]

You should post your VI; a better design will help you take advantage of the resources on your machine. Right now, it seems like your user interface thread is choking the system. Have a look at the Producer/Consumer design pattern (File -> New...).

[Charlie_P]

Good Afternoon Ledge,

This is most likely a LabVIEW programming issue, though it is hard to say without seeing your code.  We have many resources for multicore computers.  Please see the link below for some great information.

Multicore Programming Resources

     http://www.ni.com/multicore/

[Ledge]

Gentlemen, Thanks for your input, but I have solved the problem.

I simply cut and pasted the Front Panel onto a new VI, re-did the wiring diagram (exactly the same), and everything now works fine.

I don't know what caused the problem, or why this fixed it, but it did.

The only thing I noticed was that the bars at the right hand side and bottom of the screen (the ones that move the front panel around, like the pale blue one on the RHS of this screen) were very short. That is, my front panel icons, though they filled the entire visible screen area, were only taking up a very small proportion of the available front panel space. I hope this makes sense to someone.

I have also noticed that the use of property nodes within loops - changing properties on the fly - can slow VIs significantly. Has anyone else seen this?

Regards

[Charlie_P]

Good Morning Ledge,

Thank you for posting the update; I am glad you were able to get that working.  From your description, it seems that your original VI was corrupt.

Hopefully you are taking advantage of all those cores, too.