[ECOS] suspend/resume nesting

Thomas Koeller thomas@koeller.dyndns.org
Tue May 20 20:11:00 GMT 2003


On Tuesday, 20. May 2003 21:00, Eric Donnat wrote:
>
> I'm not sure that only such a patch is the solution to this issue.
>
> I remember reading somewhere the suspend/resume were only to be used
> to implement some kind of debugging tricks. If I understand your
> point of view you are trying to use them in order to implement a
> kind of synchronous thread RPC. The problem of such services is
> much complex than exposed here because they could lead to priority
> inversion issues when more than three threads are playing with them.
>
> From my previous experience, I found than implementing synchronous
> mechanisms never requires suspend/resume, from the fact that
> eCos is already exporting all what you need via existing synchronization
> primitives (such as flags), thread priority control, and scheduler
> control. IMHO, suspend/resume is like playing with fire.
>

Both cyg_thread_suspend() and cyg_thread_resume() are officially
documented API functions, and so they should be usable. Other
synchronization mechanisms may be built upon them. I also
think there are valid uses for them, and I have been using such
mechanisms sucessfully through the years. Of course, you have
to know what you're doing, but thats true for any other programming
construct as well.

tk

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Thomas Koeller, Software Development

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