The C# libraries either invoke the native Linux libraries directly or go throw a thin wrapper[1] that does the normal things you have to do to support multiple

The C# libraries either invoke the native Linux libraries directly or go throw a thin wrapper[1] that does the normal things you have to do to support multiple flavors of Unix (epoll vs kqueue, etc). Parts of the C++ runtime are written in terms of the Win32 API and on Unix these API are implemented in the PAL[2]. The PAL is not that big and I don’t the steady state performance critical code paths go through it. 1: https://github.com/dotnet/runtime/tree/master/src/libraries/Native/Unix/System.Native https://github.com/dotnet/runtime/tree/master/src/libraries/... 2: https://github.com/dotnet/runtime/tree/master/src/coreclr/src/pal https://github.com/dotnet/runtime/tree/master/src/coreclr/sr...