Re: Self restarting property of RTOS-How it works?

From: del cecchi (dcecchi.nojunk_at_att.net)
Date: 02/12/05 

Date: Sat, 12 Feb 2005 10:07:00 -0600

"Ed Beroset" <beroset@mindspring.com> wrote in message
news:uvpPd.19360$wK.11885@newsread3.news.atl.earthlink.net...
> Del Cecchi wrote:
> > Ed Beroset wrote:
> >
> >> I have also noticed that the programmers from a computer science
> >> background tend to be much better at working out a system
architecture
> >> and planning first.
> [...]
> >>
> > Those comp-sci geniuses are the ones that gave us a software
paradigm
> > that is susceptible to attacks as simple as buffer overruns, and
store
> > data in randomly scattered chunks linked by pointers. And put
multiple
> > unrelated locks in the same cache line? That the ones you are
talking
> > about?
>
> It's interesting to learn that no engineers were ever involved in
> building such flaws.
>
> My background happens to be more in the engineering than the computer
> science end of things, but I don't share your evident contempt for the
> field. Here's an example: An embedded communication system receives
> packet-based messages of varying lengths at an average rate of 100
> packets per minute, but asynchronously. Because the system also
checks
> its timing against the recovered clock from the messages, which it can
> easily keep synchronized within limits as long as it doesn't go too
long
> without receiving a packet. What is the probability that no packets
> will arrive in an interval of five seconds?
>
> I can answer that question easily because I've studied a little
computer
> science. Can you? If not, how can you properly engineer the system?
>
> Ed
Well, first I would want to know the average utilization of the link.
Then I would want to know the distribution of the lengths of the
packets, and the distribution of the rate at which they are sent. If
the distribution is that the utilization is 0.1 percent and the packets
are all sent once a minute by a batching system then the probability is
100 percent. On the other hand if the utilization is 99.9 percent and
the distribution is uniform, then the probability is very low.

Yes, I too have studied some computer science. The first time I saw
some of the algorithms, and the scheme language, I almost plotzed.

del cecchi
>

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