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CPU Load Control

By , 22 Feb 2007
 
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Introduction

This is a basic MFC program that demonstrates how to retrieve the current CPU load percentage and set it using a high priority thread control loop. I created this project simply because I needed to test another fairly time/buffer critical application and wanted to simulate heavy amounts of CPU load and/or a slower computer. By using this app, you can successfully "steal" away certain amounts of processor instructions to emulate slower or more heavily loaded machines.

It only fully works on single core systems. I personally have a dual core machine, and therefore the one thread that runs in this program can never utilize more than 50% of the "Total Processor Load." I tried launching multiple threads that would hopefully use both cores, but it didn't work - I'm guessing you would have to somehow instruct a 2nd thread to use your second core. Anyway, it wasn't worth it for me to implement, so if anyone wants to add full support for multi-core machines, please post how it's done to others.

Included is a project built using VS 2005. The code is very simple and could be easily added to another project. To retrieve the CPU load percentage, you must include the dependency pdh.lib in your Project->Linker settings.

History

  • 22nd February, 2007: Initial post

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

jkhax0r
United States United States
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GeneralNot work in one core PC with Windows2000 ProfessionalmemberAleksMain27 Feb '07 - 2:24 
I tested your demo execution file and didn't see any blue bar or percent of loading for processor. Any percent entered by me manually equally didn't work.
 

 
AleksMain

GeneralRe: Not work in one core PC with Windows2000 Professional Pinmemberjkhax0r2 Apr '07 - 6:38 
Sorry for late reply. The calls to measure CPU load are somewhat black magic to me as it is merely a call to the Windows API.
 
The function OnTimer is called every ~1 second to update the CPU load percentage. This function calls an internal function GetCPUCycle() which then calls the windows API functions PdhCollectQueryData() and PdhGetRawCounterValue() to get the CPU load percentage. These Pdh functions are where all the magic happens and unfortunately I am not very familiar with them as I just used an example for how to measure CPU load for the sake of controlling it. Perhaps the implementation is wrong. I would suggest looking in MSDN documentation for an example of how to use these. It may be a problem in your version of MFC or possible of the DLL that the Pdh functions use. The person in the above post may have experienced this same problem when he or she had so much "trouble" porting to VC6.0.

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