how to set timer resolution from C# to 1 ms?

Question

I've used this tool and noticed that my Windows Server 2008 R2 Standard has a 15 ms resolution while Windows 8 has a 1 ms resolution timer.

I would prefer to set the Timer Resolution to 1 ms on Windows Server 2008 R2 because I'm running low-latency software on it.

I've found this msdn article, but it doesn't explain how to change the Timer resolution from a C# program. How do I do that?

Answer 1

You can try this:

public static class WinApi
{
    /// <summary>TimeBeginPeriod(). See the Windows API documentation for details.</summary>

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Interoperability", "CA1401:PInvokesShouldNotBeVisible"), System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Security", "CA2118:ReviewSuppressUnmanagedCodeSecurityUsage"), SuppressUnmanagedCodeSecurity]
    [DllImport("winmm.dll", EntryPoint="timeBeginPeriod", SetLastError=true)]

    public static extern uint TimeBeginPeriod(uint uMilliseconds);

    /// <summary>TimeEndPeriod(). See the Windows API documentation for details.</summary>

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Interoperability", "CA1401:PInvokesShouldNotBeVisible"), System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Security", "CA2118:ReviewSuppressUnmanagedCodeSecurityUsage"), SuppressUnmanagedCodeSecurity]
    [DllImport("winmm.dll", EntryPoint="timeEndPeriod", SetLastError=true)]

    public static extern uint TimeEndPeriod(uint uMilliseconds);
}

And use it like this:

WinApi.TimeBeginPeriod(1);

And to go back to how it was:

WinApi.TimeEndPeriod(1);

Answer 2

Better code to implement this would be:

using System;
using System.Runtime.InteropServices;
using System.Threading;

internal sealed class TimePeriod : IDisposable
{
    private const string WINMM = "winmm.dll";

    private static TIMECAPS timeCapabilities;

    private static int inTimePeriod;

    private readonly int period;

    private int disposed;

    [DllImport(WINMM, ExactSpelling = true)]
    private static extern int timeGetDevCaps(ref TIMECAPS ptc, int cbtc);

    [DllImport(WINMM, ExactSpelling = true)]
    private static extern int timeBeginPeriod(int uPeriod);

    [DllImport(WINMM, ExactSpelling = true)]
    private static extern int timeEndPeriod(int uPeriod);

    static TimePeriod()
    {
        int result = timeGetDevCaps(ref timeCapabilities, Marshal.SizeOf(typeof(TIMECAPS)));
        if (result != 0)
        {
            throw new InvalidOperationException("The request to get time capabilities was not completed because an unexpected error with code " + result + " occured.");
        }
    }

    internal TimePeriod(int period)
    {
        if (Interlocked.Increment(ref inTimePeriod) != 1)
        {
            Interlocked.Decrement(ref inTimePeriod);
            throw new NotSupportedException("The process is already within a time period. Nested time periods are not supported.");
        }

        if (period < timeCapabilities.wPeriodMin || period > timeCapabilities.wPeriodMax)
        {
            throw new ArgumentOutOfRangeException("period", "The request to begin a time period was not completed because the resolution specified is out of range.");
        }

        int result = timeBeginPeriod(period);
        if (result != 0)
        {
            throw new InvalidOperationException("The request to begin a time period was not completed because an unexpected error with code " + result + " occured.");
        }

        this.period = period;
    }

    internal static int MinimumPeriod
    {
        get
        {
            return timeCapabilities.wPeriodMin;
        }
    }

    internal static int MaximumPeriod
    {
        get
        {
            return timeCapabilities.wPeriodMax;
        }
    }

    internal int Period
    {
        get
        {
            if (this.disposed > 0)
            {
                throw new ObjectDisposedException("The time period instance has been disposed.");
            }

            return this.period;
        }
    }

    public void Dispose()
    {
        if (Interlocked.Increment(ref this.disposed) == 1)
        {
            timeEndPeriod(this.period);
            Interlocked.Decrement(ref inTimePeriod);
        }
        else
        {
            Interlocked.Decrement(ref this.disposed);
        }
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct TIMECAPS
    {
        internal int wPeriodMin;

        internal int wPeriodMax;
    }
}

Use it via:

using (new TimePeriod(1))
{
    ////...
}