KAISER: hiding the kernel from user space [LWN.net]

KAISER: hiding the kernel from user space

Posted Nov 16, 2017 18:34 UTC (Thu) by ttelford (subscriber, #44176)
Parent article: KAISER: hiding the kernel from user space

Just the new instructions (CR3 manipulation) add a few hundred cycles to a syscall or interrupt

A few hundred cycles to a syscall or interrupt is vaguely similar to the basic IPC cost of the L4 microkernel. (200-300 cycles for amd64).

Kernels are not my area of expertise, so I have to ask: if a syscall is about to become as expensive as IPC on L4... would the (theoretical) performance of the respective kernels be similar after KAISER?

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KAISER: hiding the kernel from user space

Posted Nov 16, 2017 20:52 UTC (Thu) by hansendc (subscriber, #7363) [Link]

> if a syscall is about to become as expensive as IPC on L4... would the (theoretical) performance of the respective kernels be similar after KAISER?

Most of the KAISER performance impact is purely from the cost of manipulating the hardware. L4 and other kernels would pay the same cost Linux would.

It's not fair to compare a non-hardened kernel to a hardened one, though. It's apples-to-oranges.