[ECOS] Thread activation disturbed by lower priority threads]

Alois Zoitl alois@gmx.at
Thu Aug 16 20:05:00 GMT 2007


thanks you definitely pointed me into the right direction. The problem 
is located with the mutexes. I removed all mutexes in questions and set 
my timing measurement points directly after the semaphore that is in 
charge of activating my threads.After making more measurements and 
playing a little bit around I found it that when I set the priority 
inversion protocol to none (using cyg_mutex_set_protocol). The timing is 
as expected. So I thought it could be that before I was using priority 
ceiling which would be an explanation for the delay as every time a 
mutex is gathered the thread will get priorty 0. So I changed to 
priority inheritance. This from my point of view should do the job as I 
like to have it done.
But when using priority inheritance I get the same bad timing as in the 

And as longer I think I don't know why the tread activation of the 
highest priority thread is prolonged by threads holding a mutex with 
priority inheritance where each of the treads that my also get this 
mutex has a lower priority. So I'm completly confuesed. Any Ideas what 
could be the problem or what I could do?

For my current tests no priority inversion protocol is just fine, but 
for further more complected tests I think i will need something like 
priority inheritance so it would be nice to have it.


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