[coyotos-dev] More progress, some design issues

[Christopher Nelson]

On 5/6/07, Jonathan S. Shapiro <shap at eros-os.com> wrote:
>
> On Sun, 2007-05-06 at 18:46 -0400, Christopher Nelson wrote:
> > I think that activation handlers are an extremely useful primitive,
> > and it's worth some extra work to keep them, IMHO.
>
> As a matter of personal bias, I agree, but we also need to meet
> deadlines and keep moving forward.
>
> Can you enumerate what you perceive as some of the advantages, so that
> they are placed in front of us to look at explicitly?
>
>
My personal opinion is that activation handlers allow you to do asynchronous
notifications of many types essentially 50% cheaper than other comparable
methods - from both a space and transit time perspective.  They also allow a
much more elegant form of preemption than other methods.

Using most other forms you have to either poll (bad) or have a heavy
full-time thread manage notifications (usually blocking on some sort of
mutex.)  You also generally have to have two ring transitions with the
associated baggage.

It seems to me that, especially in real-time applications in embedded
systems, you would want to make use of such a mechanism.

Many (most?) of the in-practice software errors I deal with on a day-to-day
involve blocked threads, race conditions, and bad timeout assumptions.  It
seems to me that considered use of activation handlers can eliminate the
need for these constructs in many places.

-={C}=-
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