What did throttle my “Parallel.For” application?

Question

What did throttle my “Parallel.For” application?

alp imrek 1

With using VS2019, C#.net 5.0 I wrote an application that calculates the distance matrix of 16000 points to 16000 points with two nested Parallel.For:

    Parallel.For(0, countA, k =>
    {
        Parallel.For(0, countB, i =>
        {
            SumofSquareDifference(k, i);
        });

    });

it runs with 77%-99% CPU load on first run. It's registered in Computer\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\bam\State\UserSettings\ with EXE's location On the second run, it does not allow the CPU load to exceed 20%. If i move the project directory, application runs again at %99 for once. I think it is throttled by Windows. How can I run it with 99% CPU load?

I uninstalled the antivirus.

Windows Edition:

Windows 10 Home Single Language Version 21H1 Installed on ‎21/‎11/‎2020 OS build 19043.985 Experience Windows Feature Experience Pack 120.2212.2020.0

Power options, Advanced settings,

Processor power management

Minimum processor state: On battery : 100% Plugged in : 100%

System cooling policy: On battery : Active Plugged in : Active

Maximum processor state: On battery : 100% Plugged in : 100%

Timon Yang-MSFT 9,606 Reputation points

2021-06-29T06:34:18.007+00:00

@alp imrek
Will the same problem occur when using a normal for loop instead of Parallel.For?
It should be the code that you did not show that is causing the high CPU usage. Could you please provide a minimal case that can reproduce the problem so that we can test it?
Timon Yang-MSFT 9,606 Reputation points

2021-07-08T08:53:52.297+00:00

@alp imrek
Do you still meet this issue? If so, could you please share more detailed information?

Your answer

Timon Yang-MSFT 9,606 Reputation points

2021-06-29T06:34:18.007+00:00

@alp imrek
Will the same problem occur when using a normal for loop instead of Parallel.For?
It should be the code that you did not show that is causing the high CPU usage. Could you please provide a minimal case that can reproduce the problem so that we can test it?
Timon Yang-MSFT 9,606 Reputation points

2021-07-08T08:53:52.297+00:00

@alp imrek
Do you still meet this issue? If so, could you please share more detailed information?

Share via

What did throttle my “Parallel.For” application?

Your answer