Periodic Timing Issues with PXIe-8135 RT

[Sneaker]

I have been having periodic timing issues for a while now that I can't seem to get to the bottom of. Here are some details into my DLL - RT DLL built in LabWindows/CVI in release mode - 8 threads are time critical, 6 run @ 1KHz, 2 @ 100Hz - equal number of consumer threads for data logging at lower priority - I take a CVIAbsoluteTime timestamp at the beginning of every procedure call - Every 90s I start seeing "blips" for a period of time usually around 8s then it goes back to normal - For an example at 100Hz: the "blips" I see show the callback intervals at ~0.011s vs the expected ~0.010s - This happens in all threads - It's always done this regardless of the state of the software and any configuration I've ever run Does anyone have any insight into what may be causing these timing issues? I've scoured the internet for answers and found nothing. I'll attach some screenshots produced in MatLab by calling diff on normalized timestamp data

[Sneaker]

normal scale screenshot

[thuyanhl]

Hi,

I am not sure I understand your question.

Is the difference of 0.001 sec between the start of your threads and you are expecting them to start at the same time? Could you explain what you mean by blips?

[Sneaker]

What I mean is that I expect a callback function to be called every 0.01s (100Hz). Periodically the functions will all be called at 0.011s after the last procedure call.

[Sneaker]

I just realized the snapshots never got posted. These were produced in Matlab calling the diff function on the normalized timestamp data when calling CVIAbsoluteTime()