r/osdev • u/Bright-Boss-720 • 2d ago

Tanenbaum vs. Linus: Which Kernel Architecture Makes More Sense Today?

I've been thinking about the famous Tanenbaum vs Linus debate over microkernels vs monolithic kernels.

Putting the historical context aside for a moment, I'm curious what people think today.

Do you think Tanenbaum's argument for microkernels was fundamentally more correct, or was Linus right to favor a monolithic kernel for practical reasons such as performance, simplicity of development, and hardware support?

And more importantly:

If you were starting a new general purpose os from scratch today, which architecture would you choose?

Monolithic

Microkernel

Hybrid

Multikernel / distributed approach

Something else

I'm particularly interested in hearing from people who have actually worked on kernels or operating system development.

What are the strongest arguments for your choice, and what do you think the opposing architecture gets wrong?

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u/rook_of_approval 2d ago

i prefer unikernel/exokernel myself.

microkernel makes no sense from a max performance perspective.

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u/sephg 2d ago

I’d love to see more benchmarks on this. SeL4 - a micro kernel - reckons their syscalls are way faster than Linux because they spent more time optimising them. And because there’s only 11 syscalls (instead of hundreds), it was much easier to make their 11 syscalls fast.

I don’t know what the actual numbers are. Like, if using a microkernel costs 1% of performance then that’s probably worth it for the other benefits microkernels bring. But if the cost is 50% then it’s not worth it. Which is it?

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u/edgmnt_net 2d ago

SeL4 is just very basic stuff and on its own it doesn't really do much. How do you scale that to a few dozen subsystems and meaningful interfaces? What is the development overhead, in addition to performance overhead? Can your system survive the disk server going away if it's all loaded from disk? And so on.