[ECOS] Thread activation disturbed by lower priority threads]

Alois Zoitl alois@gmx.at
Thu Aug 23 20:38:00 GMT 2007


Hi

> To have more detailed info about this, you could turn on kernel
> instrumentation and enable CLOCK, MUTEX and SCHEDULER events. For more
> info, see here :
> http://ecos.sourceware.org/docs-latest/user-guide/kernel-instrumentation.html

I tried a little bit with the kernel instrumentation, but could not get 
any results I could handle.
What i did was to further investigate which of my mutexes was the 
problematic one. And it is the one
I initiali thought will make a problem.

This mutex locks at some stage each of my threads. As soon as I remove 
this mutex (with special test apps this is not a problem) the scheduling 
is as expected. As soon as I add the mutex I get the problem again. Even 
the thread which is disturbed will access the mutex later in its 
execution its activation is delayed. It looks as this mutex gets an very 
high priority although I use priority inheritance.

For my current test I found it that priority inversion will not be a big 
problem. At least currently. So i'm fine without a priority inversion 
protocol.
Nonetheless Its ok for me to further investigate the problem if I can 
help to improve eCos.

cheers
Alil

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