CPU load over time

[cviuser167]

Here's an interesting phenomenon that I haven't been able to figure out: I start my application (2 channels AI at 1500 Hz each, 1 serial channel at 75 Hz, real-time graphing and streaming to disk) and the CPU load jumps to 80-90%. After about 30 seconds, the load drops down to about 10%. Everything is still running and streaming to disk but the load just drops. I've used the profiler but that only seems to tell you about subVIs that are called and not which loops of a VI are taking up the most time.

Any thoughts?

-dennis.

[Joe_Guo]

Could you be more specific? It sounded like a standard behaviour. Everytime when I open IE or Word it takes nearly 100% CPU for the first couple of seconds.

-Joe

[cviuser167]

Once the application is fully loaded and then I hit the Run arrow, the CPU load hits 80-90% for the first 30 seconds or so of run time. Then it drops down to the expected 10-20% range. If I stop the app and then hit the Run Arrow again, I get the same behavior.

[Joe_Guo]

It could be the hardware initialization. It's hard to say without studying the code.

-Joe

[Brett_B.]

Dennis,

Are you seeing any system performance decrease? Quite often, even if the CPU is listed at 100%, the resources are listed at an extremely low priority. This means that ANY program that requests resources will cause LV to make some available. This is common in the DAQ calls.

hope this explains it,
Brett