[En-Nut-Discussion] Thread priority

[Michel Hendriks]

Yes, I see what you are saying. That is why we sleep 100ms in that thread:

    NutThreadSetPriority(1);
    for (;;)
    {
        NutSleep(100);
        WatchDogRestart();
    }

Our watchdog is set to 2 seconds, so there should be enough time
even if a thread would use 1,89999 seconds before releasing the CPU.


The reason I want to give this watchdog thread the highest priority
is because I found that, if I am busy in another thread, that thread
will not give back the CPU if it uses a higher priority. Even when using
the same priority, NutOS will not give time to the watchdog thread.

So if I would have a thread doing this:
    NutThreadSetPriority(1);
    for (;;)
    {
        DoSomethingFor1.8seconds();
        NutThreadYield();
    }

I would get watchdog resets. If I lower the prio of the other thread,
the watchdog thread always gets its turn.

Greets,
Michel Hendriks


> -----Oorspronkelijk bericht-----
> Van: en-nut-discussion-bounces at egnite.de 
> [mailto:en-nut-discussion-bounces at egnite.de] Namens Ole Reinhardt
> Verzonden: woensdag 16 mei 2007 11:34
> Aan: Ethernut User Chat (English)
> Onderwerp: Re: [En-Nut-Discussion] Thread priority
> 
> Hi,
> 
> > Maybe, but I want to check if my threads are still running.
> > The easiest way to do that is using a high prio thread :-)
> 
> You might do so. But be aware that if your thread has the 
> highest priority it will always run if you don't use NutSleep 
> to explecitly wait some time. Of course you could also wait 
> on events etc.
> 
> In other words: Your watchdog threads _needs_ to give back 
> the cpu and you may not do this by using NutThreadYield() as 
> you would directly gain back cpu time.
> 
> Normaly it should be fine to run the watchdog with lower 
> expiration time and use a normal priorised thread.
> 
> Best regards,
> 
> Ole Reinhardt
> 
> 
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