FW: Accuracy of rtems_timer_server_fire_after

Sebastian Huber sebastian.huber at embedded-brains.de
Wed Jul 4 11:38:59 UTC 2012

Hello Mogens,

On 07/04/2012 11:38 AM, Mogens Dybæk Christensen wrote:
> Hi
> Does the server task behind these delays run at clock tick speed, or is the
> timing scaled down?

the timer server task is triggered by the system clock interrupt.


> The system tick is 1 mS, but if (as an extreme test)
> rtems_timer_server_fire_after is fed with a 1 tick delay, the callback routine
> is called after approx. 29 mS!

This should not happen provided the timer server task execution is not delayed. 
  Is it really the highest priority task at this moment?  Are some running 
tasks non-preemptible?


Sebastian Huber, embedded brains GmbH

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