Re: Why kernel REVOCABLE COPY is difficult

[Jonathan S. Shapiro]

On Mon, 2005-10-10 at 03:12 +0200, address@hidden wrote:
> 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.

There exist processors that do context switch perfectly well. Even so,
the IA32 will remain the most important target for a long time, and on
that platform things are getting steadily worse.

shap