How to empty/flush Windows READ disk cache in C#?

Constantin: Thanks! That link has a command-line EXE which does the testing I was looking for.

I also found a link off that page to a more interesting article (in Word and PDF) on this page: Sequential File Programming Patterns and Performance with .NET

In this article, it talks about Un-buffered File Performance (iow, no read/write caching — just raw disk performance.)

Quoted directly from the article:

There is no simple way to disable
FileStream buffering in the V2 .NET
framework. One must invoke the Windows
file system directly to obtain an
un-buffered file handle and then
‘wrap’ the result in a FileStream as
follows in C#:

    [DllImport("kernel32", SetLastError=true)]
    static extern unsafe SafeFileHandle CreateFile(
        string FileName,           // file name
        uint DesiredAccess,        // access mode
        uint ShareMode,            // share mode
        IntPtr SecurityAttributes, // Security Attr
        uint CreationDisposition,  // how to create
        uint FlagsAndAttributes,   // file attributes
        SafeFileHandle  hTemplate // template file  
        );

    SafeFileHandle handle = CreateFile(FileName,
                            FileAccess.Read,
                            FileShare.None,
                            IntPtr.Zero,
                            FileMode.Open,
                             FILE_FLAG_NO_BUFFERING,
                            null);

    FileStream stream = new FileStream(handle, 
                    FileAccess.Read, 
                    true, 
                    4096);

Calling CreateFile() with the
FILE_FLAG_NO_BUFFERING flag tells the
file system to bypass all software
memory caching for the file. The
‘true’ value passed as the third
argument to the FileStream constructor
indicates that the stream should take
ownership of the file handle, meaning
that the file handle will
automatically be closed when the
stream is closed. After this
hocus-pocus, the un-buffered file
stream is read and written in the same
way as any other.