w3k3m :
Performance hits in microkernel IPC may occur because of message passing copying overhead. This became largely irrelevant with modern and efficient mikrokernels (eg. QNX, L4). Think RISC vs CISC.
I didn't say either that changing Linux kernel architecture now would be attainable. I was just trying to say that monolithic architectures are doomed and one of the reasons why Linux faces these manageability problems. Another analogy would OOP vs procedural code managing. It is just pathetic that Linus talks about these problems and won't say a word about his mistakes. Instead he just says "we must make things simpler". Good luck reaching 100 million lines of code.
Again you've shown you don't actually know what your talking about, RISC vs CISC is not a comparison, there is no such thing as "CISC", mere "not RISC". RISC isn't a processor design, its a set of principles that are recommended for engineers to follow. I could write a book about this subject.
There is ~ALWAYS~ a performance penalty with micro-kernels, its the natural result of heightened security and restricted communication between process's. That is the only difference between a macro and a micro kernel, the level of modularization that occurs. Only way around that is to give driver modules direct access to kernel memory space and the memory space of other modules, which invalidates the entire reason for having a micro-kernel to begin with.
Now onto your complete lack of processor micro-architecture knowledge. Currently in the world there is no "not RISC" CPU's being made. Intel / AMD CPU's are RISC CPU's internally. Their various processor resources (MMU / ALU / AGU / FPU / Register File) are all designed using RISC principles. What they do is put a front end decoder / scheduler that intakes the binary x86/87 machine code and converts it into their proprietary RISC language and then forwards it to the various processor elements for processing. Once the results are finished they return those results to the program. This was done to maintain backwards compatibility with previous code.
Backwards compatibility is what drives the entire world. The computing world is not an authoritarian dictatorship, no single entity nor group of entities can rewrite world wide standards overnight. It takes years for standards to be adopted, and even longer for older standards to fade into obscurity.
If you think otherwise, if you think that your some all knowing paragon of programming skill, then write your own OS and make it successful. Anything else means your just pissing in the wind.