Re: Few questions on embedded stuff

From: Andreas Hadler (Andreas.Hadler_at_t-online.de)
Date: 06/28/04

  • Next message: Johan Borkhuis: "[comp.os.vxworks] FAQ - index" 
    Date: Mon, 28 Jun 2004 19:25:22 +0200

    Rick Merrill <RickMerrill@comTHROW.net> wrote:

    >Andreas Hadler wrote:
    >
    >> Rick Merrill <RickMerrill@comTHROW.net> wrote:
    >>
    >>>Right. But a complex system with lots of resource locks can get into
    >>>unanticipated states, and one of those might require an automatic
    >>>reboot - by the WDT. - RM
    >>
    >>
    >> That's the answer, that horrifies me.
    >
    >Suppose you have 5 processes and 5 resources used (let's say)
    >by each process: how many permutations would that be, and can you
    >think of a way to check out all those timing possibilities? - RM

    Just request them in the same order in all processes. In the flow of
    logic of any process do
    lock 1
    free 1
    lock 2
    free 2
    lock 3
    free 3

    or
    lock 1
    lock 2
    free 2
    lock 3
    free 3
    free 1

    Never go 1-2-3 in one and 1-3-2 in another process. Nevertheless, you
    can go 1-2-3-4 and 1-2-4 and 1-3-4 in different processes.

    To make this possible is called design. You can even resort to one
    super-resource, though your timing may suffer by this approach.

    Andreas 

    -- 
Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are, by
definition, not smart enough to debug it.
- Brian Kernighan
  • Next message: Johan Borkhuis: "[comp.os.vxworks] FAQ - index"

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