Tick interrupt priority?

groups at chichak.ca groups at chichak.ca
Thu Sep 19 04:31:45 UTC 2019

Super, I’ll have to review my projects to see if I did it right.

Granted, it should only come into play when there is interrupt contention, but these are the sorts of things that cause subtle issues.

Thanks Chris,


> On 2019-September-18, at 22:32, Chris Johns <chrisj at rtems.org> wrote:
> On 19/9/19 2:16 pm, groups at chichak.ca wrote:
>> I was reviewing the interrupt priorities on a project where I’m using FreeRTOS and they want the tick interrupt priority to be very low.
>> I found this to be not obvious, then started wondering what the elders of the RTEMS suggest for use with RTEMS.
>> Should the tick interrupt be high priority or low?
> If all that is happening is the OS tick entry point is being called then I set
> the priority below any other sources. If the OS tick routine expires a timer and
> readies a task that task will not be dispatched until the outer most interrupt
> exits so being any higher does not gain you anything.
> Chris

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