Native C++ performance using C# or within C#

I was wondering if the two following scenarios have the same performance impact on native C++ code (if there is any performance impact at all).

Let's assume I have the function cpp_calc() that is doing some calculation stuff and is written in native C++. Also, there is cs_show_gui_stuff(), which is written in C#.

Now, which of the following scenarios will w开发者_JAVA技巧orsen the native c++ performance (if there is any performance penalty at all)?

1. Creating a .Net (C#) application that runs cs_show_gui_stuff() and calls cpp_calc() in the native C++ dll using DllImport or turning C++ into a COM DLL.

2. Creating a C++ application that implements cpp_calc() in C++ and runs cs_show_guid_stuff() by placing the C# code in a .Net COM DLL.

Thanks :-)

It really depends on what the other parts of the system are mainly written in. From a performance-only perspective, one PInvoke (via DllImport attribute) call will probably be faster than one COM call if the method arguments do not need any special marshaling.

A third, and probably the best alternative, is to create a managed C++/CLI library that calls the unmanaged C++ method with nearly no performance impact and add a reference to the C++/CLI library in the C# application. The C# application can then make managed method calls to the C++/CLI application, which in turn can make unmanaged method calls. While this adds one level of indirection, it will provide way better performance than the methods you mentioned.

Either way You are going to bump on Just-In-Time compiler. I guess the penalty is the same on both scenarios. I would personally choose the first one, because .NET libs are more robust on the GUI - WPF, Silverlight, WinForms, WebForms, Razor ... You see what I mean.