You could do worse than Mach ports

[ibotty]

Kip Macy wrote:

> Although some of the communication primitives are reminiscent of
> microkernels, and there is the intent of moving some things into
> user space, he wants to avoid having applications pay the performance
> penalty in the common case. L4 is a dramatic improvement over Mach,
> but L4Linux had to be tuned to an incredible degree to get it to the
> 96% of native Linux that they quoted. These days with the improvements
> that have been made in Linux 2.4 your looking at 65% of native.

the l4 benchmarks you have in mind may well be the above an l4v2 api.
l4 version 4 (X.2) has much improved the situation.
but l4linux is one big l4 thread, w/o many advantages to monolithic linux.

> His emphasis is much less on protection boundaries because of the
> cost that one tends to incur from them.

l4 allows processes (threads) with shared memory between both processes.
its just easy to seperate them.
( you might be aware of this, but just to point this out )

~ibotty