Messages in this thread |  | | From | Alan Cox <> | Subject | Re: Linux and Microkernels (was Re: your mail) | Date | Thu, 25 Jul 1996 09:52:19 +0100 (BST) |
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> >>>>> "AC" == Alan Cox <alan@lxorguk.ukuu.org.uk> writes: > AC> A monlithic OS is faster than a microkernel based system. > > Statements about "all micro-kernels" based on experience with Mach will > guarantee incorrect results. The speed argument is not true any more.
I'm working on benchmarks of three microkernels, including AmigaOS which had a microkernel done right, and not Mach which (IMHO) is a mess, although OSF mach is looking nice.
> what the interrupt latency of Linux on a 486DX2-66 is, but under QNX > it is 4 microseconds. In fact, QNX's performance is so well tuned and > fast that it is used heavily in industrial real-time processing > applications.
QNX is specifically designed for hard real time. You'll notice that it uses things like single page table sets to get performance. For a generic application any "microkernel" will be slower because you either
a) Have message passing overhead of some form (which costs instructions) or b) Its not really a microkernel at all, its just a well structured monolithic kernel like Linux is now
Alan
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