Re: Why kernel REVOCABLE COPY is difficult

[olafBuddenhagen]

Hi,

> The one thing that makes me put these in-kernel heaps on the "deferred"
> list rather than the "forget" list is my concern that hardware context
> switch performance is getting steadily worse, and that microkernel
> designs may have to compromise purity to remain competitive. This is
> disturbing, but it may be inevitable.

Is it really getting worse? I read that someone managed to bring L4 IPC
on Itanium down to 36 cycles. In view of the *theoretical* scalability
of the different processors, this seems about similar to the 121 cycles
L4 claimed on Pentium 1.

Considering that the theoretical scalability is increasingly becoming
harder to fully exploit in practice on newer processors, I tend to
believe the relative IPC cost is actually lower on Itanium...

-antrik-