[ECOS] eCos Interrupt timing

[e.coullien@faiveley.com]

Hello,

We try to understand what ecos is doing when receiving an interrupt.
We modified temporally the file vector.S to trace on a logic output a signal
that represent how long is the interrupt time process
In this file, we set the signal before the context saving and we unset it just
before the context restoring
Then on the oscilloscope, we see that the signal is set at every tick system and
it is unset  500us (for a tick of 1ms) later.
During this time, The Decrementer ISR is executed (100 us) then interrupt_end().
It seems most of the time is spent in cyg_scheduler::unlock().
We don't understand what does ecos during these 400us (500-100).
Does somebody have an idea ?

Thanks,

Emmanuel Coullien



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