Why is CONFIG_MAIN_THREAD_PRIORITY=7 in mqtt_simpe?

RE: Why is CONFIG_MAIN_THREAD_PRIORITY=7 in mqtt_simpe?

Martin Lesund — Thu, 05 Dec 2019 10:28:25 GMT

That depends on what you are planing with your application.

You do not need to change it, but you could if you want some threads to be prioritized over the other.

To understand how this works I would recommend checking out the documentation links posted in my last post.

Yusuke — Thu, 05 Dec 2019 09:31:40 GMT

I see. So I shouldn't basically change the value, right?

Martin Lesund — Thu, 05 Dec 2019 08:15:32 GMT

Hi Yusuke,

Yes, since the main thread is a preemptible thread it can have non-negative priority values. (e.g. 0,1,2,3..)

Just set the value inside the prj.conf:

CONFIG_MAIN_THREAD_PRIORITY=7

This will affect how the scheduler allows the threads to share the CPU.

More details on this are described in the Scheduling documentation.

Best regards,
Martin L.

Yusuke — Thu, 05 Dec 2019 05:30:21 GMT

Thanks!

I see. Can I configure CONFIG_MAIN_THREAD_PRIORITY=1,2,3,4,5 or 6?

Martin Lesund — Wed, 04 Dec 2019 13:01:14 GMT

Hi Yusuke,

Lower values mean higher priority.

Typical values in NCS are:

-2 for MCUboot

0 for SPM

7 for regular applications