Re: Esthetics (or worse?) of Secure Pointers

[Fergus Henderson <fjh at cs dot mu dot oz dot au>]

On 18-Apr-2001, Robert Bernecky <bernecky@acm.org> wrote:
> Think of John's proposal as a stepping stone. We introduce a new
> architecture (bounded-x86) that lives alongside the existing
> x86 architecture. In the fullness of time, everyone buys
> into the secure-x86 architecture, we retire the x86 architecture
> completely, and everyone lives happily ever after.
> 
> Will this work? I believe that there are strong
> engineering and liability reasons that will make it work.
...
> John's position, and mine, is that good optimization work should
> let us get the cpu time overheads down to acceptable levels.
> We are stuck with the memory overhead, but memory is cheaper
> every day, so that's probably acceptable, particularly now that
> 64-bit architectures are becoming reasonably priced.

If you can't avoid significant memory overhead, then due to memory
hierarchy effects you're going to have an unavoidable significant
time overhead for a lot of applications.  Memory may be cheap, but
cache is still expensive, and on-chip cache sizes are limited by
the technology.  CPU speeds are increasing faster than memory speeds,
so more and more applications are limited by memory bandwidth.

So, although I admire your aims, I don't see the bounded-x86 architecture
replacing x86 any time soon.  Rather, the two will have to coexist.

-- 
Fergus Henderson <fjh@cs.mu.oz.au>  |  "I have always known that the pursuit
                                    |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.