Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>>> 2. How much slower would the whole contraption be? (I'm guessing it 
>>> would make Vista look *fast*...)
> 
>> It would be about 30% faster.
> 
>   If it would indeed by 30% faster, that would only be a sign that the
> current codebase sucks. (Of course being MS, that would hardly surprise
> anyone.)

No. It's the same codebase, one running under the OS doing VMM, address 
mapping, and kernel ring protections, the other running under the OS with 
that turned off. If you actually turn off bounds checking, you get another 
5% speed increase.

But just like staying in the cache gives you good performance, not 
*flushing* that cache every time you (say) allocate a block of memory or get 
an interrupt helps. Not having to do VM map lookups helps a bunch too. The 
numbers and costs of different bits of hardware are all analyzed separately, 
so you can decide if you like having (for example) virtual memory but not 
needing kernel trap protection ring overhead.

You don't get the 30% increase in speed from using a safe language. You get 
the ability to turn off protection from other users from using a safe 
language, which in turn gives you speed. If you want to use AmigaOS, with no 
protection from other users blasting your memory, then you would see about a 
5% performance decrease for the bounds checking.

http://research.microsoft.com/apps/pubs/default.aspx?id=71996
This points to a paper published at ACM SIGPLAN, which of course you'd have 
to pay for, but if you grope around the project you can find it in the 
source code I think. (Unless they took it out since I downloaded it.)

http://channel9.msdn.com/shows/Going+Deep/Singularity-III-Revenge-of-the-SIP/ 
has an extensive interview about "software isolated processes". Check 
starting about 30 minutes in. I'll see if I can dig up the actual URL to the 
paper with the graphs and such in it free, when I next dig out my "old 
stuff" disk.

-- 
   Darren New, San Diego CA, USA (PST)
   The NFL should go international. I'd pay to
   see the Detroit Lions vs the Roman Catholics.

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