Monitoring the CPU Usage of a LabVIEW Real-Time Target

These debugging utility VIs for the LabVIEW Real-Time Module ETS allow a user to view CPU usage information per priority, thread, and overall. This provides programmatic access to information similar to that provided by the Real-Time System Manager. The attached library includes examples illustrating how to use the functions. Please refer to the Context Help for documentation of the individual functions. Overhead is added to the system when logging CPU information is enabled; therefore it is recommended that logging be disabled when it is not being used.

Notes:
You will notice that even when no applications are running, this VI shows between 10%-30% of CPU usage (100% on FieldPoint). This is due to processes running in the background at low priorities. If you run a time-critical task, you will still have 100% of the processor available.

Time-critical priority tasks preempt these low priority processes. Therefore, a VI set to time-critical priority receives 100% of the CPU resources.

The LabVIEW RT 7.0 VIs will only run on PXI controller targets and do not provide priority or thread information.

When using the LabVIEW RT 7.0 VIs, logging is always enabled and the overhead will always be present when they are loaded into memory.

Requirements

Filename: rt_cpu_usage_71.llb

Software Requirements

Application Software: LabVIEW Full Development System 7.1
Toolkits and Add-Ons: LabVIEW Real-Time Module 7.1
Language(s): LabVIEW

Hardware Requirements

Hardware Group: Real-Time (RT)

Filename: rt_cpu_usage_820.zip

Software Requirements

Application Software: LabVIEW Full Development System 8.2
Toolkits and Add-Ons: LabVIEW Real-Time Module 8.2
Language(s): LabVIEW

Hardware Requirements

Hardware Group: Real-Time (RT)

Filename: rt_cpu_usage_8.0.llb

Software Requirements

Application Software: LabVIEW Full Development System 8.0
Toolkits and Add-Ons: LabVIEW Real-Time Module 8.0
Language(s): LabVIEW

Hardware Requirements

Hardware Group: Real-Time (RT)

Filename: rt_cpu_usage_70.zip

Software Requirements

Application Software: LabVIEW Full Development System 7.0
Toolkits and Add-Ons: LabVIEW Real-Time Module 7.0
Language(s): LabVIEW

Hardware Requirements

Hardware Group: Real-Time (RT)

Reader Comments | Submit a comment »

I'm trying this in an sbRIO board and LV 2009. The simple CPU usage vi returns 100%. The RT CPU usage vi returns approximately 12% in total and this doesn't seem to change when I add load to the processor. The RT task manager returns 100%. I'm not sure of what should I believe and how to really measure this... I downloaded the 8.5 version and just compiled it in LV2009.
- Paulo Martins, Fibersensing. paulo.martins@fibersensing.com - Oct 23, 2009

I'm trying this in an sbRIO board and LV 2009. The simple CPU usage vi returns 100%. The RT CPU usage vi returns approximately 12% in total and this doesn't seem to change when I add load to the processor. The RT task manager returns 100%. I'm not sure of what should I believe and how to really measure this... I downloaded the 8.5 version and just compiled it in LV2009.
- Paulo Martins, Fibersensing. paulo.martins@fibersensing.com - Oct 23, 2009

CPU VIs for Real-Time 8.5
You can recompile the VIs from 8.20.
- Michael King, National Instruments. michael.king@ni.com - Nov 20, 2007

Do we have a similar lib to be used for Realtime 8.5?
- Nov 19, 2007