Timing of events in an ISR

[Mark VanderVoord]

I am sending an event from an ISR.  The task waiting
on the event is the highest priority task in the
system (priority 5... where two others are priority
100+).  

It appears to take 150 usec on my AU1100 between the
actual interrupt firing, and the task being allowed to
run.  This processor runs at 400MHz, so this delay
sounds excessive to me.  If I poll the flag instead of
using the interrupt, I can act on it within 4 usec
(but I am obviously using up a lot more CPU time).  

What factors contribute to this delay?  Is there
anything that I can do about it?

As a side note, I noticed that there are a lot of
timing tests which come with RTEMS.  Would any of
these be useful in nailing down just how much time
these calls should take?

Thanks!

Mark S VanderVoord
Self-Guided Systems, LLC

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