RE: Thread blocking

viswa — Mon, 28 Mar 2022 05:16:08 GMT

Hi Hung Bui,

"I assume your question is about why the threads with same priority doesn't yield to each other and require you to do either k_sleep or k_yield."

This is what I needed.

I'll try your suggestion and get back to you. Thank you.

Regards

Visweswara Sarma

RE: Thread blocking

Hung Bui — Fri, 25 Mar 2022 13:31:56 GMT

Hi Viswa,

I still don't know how you configure the Threads and what inside them in both Method 1 and Method 2. Please elaborate a little bit more.

When you are running a Thread at non-negative priority it will be executed as "pre-emptive" thread and "a preemptible thread may be supplanted at any time if a cooperative thread, or a preemptible thread of higher or equal priority, becomes ready."

See the documentation on Thread priority here.

I assume your question is about why the threads with same priority doesn't yield to each other and require you to do either k_sleep or k_yield.

The important part here is that it only automatically yield to same priority thread when time slice scheduling is used. See here.

As far as I know by default CONFIG_TIMESLICING=y, however, CONFIG_TIMESLICE_SIZE=0 by default.
CONFIG_TIMESLICE_SIZE=0 means there will be no time slice (A time slice size of zero means "no limit" (i.e. an infinitely large time slice).)

I tried to set CONFIG_TIMESLICE_SIZE=100 (100ms/slice) and it seems to work for me. The Thread with no yield or sleep will be preempted by other thread when it's ready.

Anyway doing a Thread without proper yielding is not a good practice.