Re: Rate Monotonic Analysis

[alex@MIMSY.CS.UMD.EDU (Alex Blakemore)]

In article <476.237.uupcb@nitelog.com> michael.hagerty@nitelog.com (Michael Hag
erty) writes:
> At the risk of appearing to be a complete dolt, I ask, "Just what is rate
> monotonic analysis?"  I noted that a tutorial on this subject will be
> offered at this year's TRI-Ada and did not understand the description of
> the tutorial one whit!

rate monotonic analysis is a simple way to prove (ideally) that
a real time system will meet its deadlines.  It depends on a preemptive
priority based scheduler and an assignment of static priorities based on
timing requirements, not semantic importance.

Its a great advance in hard real-time design methods, and it works in practice.

its been extended to handle binary semaphores - most especially in the
priority ceiling protocol (PCP).  The main problem this protocol reduces is
that of priority inheritance.  There are extensions to deal with distributed sy
stems,
and other complications.  the theory gets more complex as you relax more
of the original simplyfing assumptions.

Ada9X supports RMS and PCP, Ada83 can with support from the compiler and a libe
ral
interpretation of some of the overly restrictive Ada83 scheduling rules.

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Alex Blakemore alex@cs.umd.edu   NeXT mail accepted