I want to create a program which can limit cpu usage of a process even when the computer is idle.
I have made a program that set priority of process, but if the computer is idle, the cpu usage can reach 95%. The process contains "element" is the process that I want to limit
private static readonly string[] RestrictedProcess = new[] { "element" };
static void ProcessChecker(object o)
{
List<Process> resProc = new List<Process>();
foreach(Process p in Process.GetProcesses())
{
string s = p.ProcessName;
foreach(string rp in RestrictedProcess)
{
s = s.ToLower();
if (s.Contains(rp))
resProc.Add(p);
}
}
foreach(Process p in resProc)
{
p.PriorityBoostEnabled = false;
p.PriorityClass = ProcessPriorityClass.Idle;
p.MaxWorkingSet = new IntPtr(20000000);
}
SetPowerConfig(resProc.Count > 0 ? PowerOption.GreenComputing : PowerOption.Balanced);
}
If the program you want to limit is not yours, there are several options:
Idle
and do not limit the CPU usage as the CPU should be used as much as possible in any case. It's OK to have your CPU running 100% all the time if there is something useful to do. If the priority is idle
, then the CPU usage of this particular process will be reduced if another program requires CPU.To suspend/resume a process that is not yours, you'll have to use P/Invoke (and this requires to have access to the process, so if you are Windows Vista or above, take care of UAC for admin rights):
/// <summary>
/// The process-specific access rights.
/// </summary>
[Flags]
public enum ProcessAccess : uint
{
/// <summary>
/// Required to terminate a process using TerminateProcess.
/// </summary>
Terminate = 0x1,
/// <summary>
/// Required to create a thread.
/// </summary>
CreateThread = 0x2,
/// <summary>
/// Undocumented.
/// </summary>
SetSessionId = 0x4,
/// <summary>
/// Required to perform an operation on the address space of a process (see VirtualProtectEx and WriteProcessMemory).
/// </summary>
VmOperation = 0x8,
/// <summary>
/// Required to read memory in a process using ReadProcessMemory.
/// </summary>
VmRead = 0x10,
/// <summary>
/// Required to write to memory in a process using WriteProcessMemory.
/// </summary>
VmWrite = 0x20,
/// <summary>
/// Required to duplicate a handle using DuplicateHandle.
/// </summary>
DupHandle = 0x40,
/// <summary>
/// Required to create a process.
/// </summary>
CreateProcess = 0x80,
/// <summary>
/// Required to set memory limits using SetProcessWorkingSetSize.
/// </summary>
SetQuota = 0x100,
/// <summary>
/// Required to set certain information about a process, such as its priority class (see SetPriorityClass).
/// </summary>
SetInformation = 0x200,
/// <summary>
/// Required to retrieve certain information about a process, such as its token, exit code, and priority class (see OpenProcessToken, GetExitCodeProcess, GetPriorityClass, and IsProcessInJob).
/// </summary>
QueryInformation = 0x400,
/// <summary>
/// Undocumented.
/// </summary>
SetPort = 0x800,
/// <summary>
/// Required to suspend or resume a process.
/// </summary>
SuspendResume = 0x800,
/// <summary>
/// Required to retrieve certain information about a process (see QueryFullProcessImageName). A handle that has the PROCESS_QUERY_INFORMATION access right is automatically granted PROCESS_QUERY_LIMITED_INFORMATION.
/// </summary>
QueryLimitedInformation = 0x1000,
/// <summary>
/// Required to wait for the process to terminate using the wait functions.
/// </summary>
Synchronize = 0x100000
}
[DllImport("ntdll.dll")]
internal static extern uint NtResumeProcess([In] IntPtr processHandle);
[DllImport("ntdll.dll")]
internal static extern uint NtSuspendProcess([In] IntPtr processHandle);
[DllImport("kernel32.dll", SetLastError = true)]
internal static extern IntPtr OpenProcess(
ProcessAccess desiredAccess,
bool inheritHandle,
int processId);
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool CloseHandle([In] IntPtr handle);
public static void SuspendProcess(int processId)
{
IntPtr hProc = IntPtr.Zero;
try
{
// Gets the handle to the Process
hProc = OpenProcess(ProcessAccess.SuspendResume, false, processId);
if (hProc != IntPtr.Zero)
{
NtSuspendProcess(hProc);
}
}
finally
{
// Don't forget to close handle you created.
if (hProc != IntPtr.Zero)
{
CloseHandle(hProc);
}
}
}
I don't know the exact command for C#, but it would be a command that gives control back to the operating system. I think in C++ it might be a delay or sleep that will do that. So the equivalent call in C# that will delay the code and give cycles back to the OS.
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