Get Child Thread IDs/PIDS for Native POSIX Board Target

[bob2oneil]

I need to run a Zephyr application using the Native-POSIX board target with real time priorities under Linux.
But, when Zephyr executes, all threads have a Linux priority of 20, which is not sufficient for real time behavior.

In my application, I can get to the main thread's PID via the pthread_self(). Using this ID, I can runtime elevate the one main thread priority. But this is only 1 of the 12 threads in the application, 11 threads are created by Zephyr itself via kernel configuration and device drivers.

I really want to preserve as much as possible the relative thread priorities assigned via the Zephyr application and configuration -- but these settings in Zephyr do not match Linux priorities.

The function zephyr_to_posix_priority in source file /zephyr/lib/posix/pthread.c looks to accomplish what I desire, that is assign a real time Linux priority to the application threads, mapping Zephyr priorities to Linux priorities BUT I am unable to get Zephyr configured to use Native Linux pthreads for the Native-POSIX board target. If that is possible, please provide some guidance.

In the absence of a solution described above, I would like to enumerate through all child threads of the main Zephyr application thread, and then reassign the thread real time priorities. One challenge in that process, would be to get not only the PID of each thread, but some other identifying characteristic (such as thread name or Zephyr assigned priority) to allow me to assign an appropriate mapped Linux thread priority.

Under Linux, I can use something like the following to get the child thread IDs, but I have no way of knowing what the thread does or the mapping:

ls /proc/924175/task
924175 924177 924178 924179 924180 924181 924182 924183 924184 924185 924186 924187 924188

Could I use something like k_thread_foreach() API to obtain all threads in the system.

Would the user_data provide information necessary to get the Zephyr assigned thread priority?

The Shell Interface "kernel threads" command for this application yields the following as a reference;

Threads:
 0x15f3680 ddlt_udp_server
	options: 0x0, priority: 20 timeout: 0
	state: pending, entry: 0x4468fa
	stack size 2048, unused 2008, usage 40 / 2048 (1 %)

*0x1686e80 shell_telnet
	options: 0x0, priority: 14 timeout: 0
	state: queued, entry: 0x45f31d
	stack size 4096, unused 4056, usage 40 / 4096 (0 %)

 0x1756ab8 rx_q[0]   
	options: 0x0, priority: -1 timeout: 0
	state: pending, entry: 0x475423
	stack size 1504, unused 1464, usage 40 / 1504 (2 %)

 0x1757ae0 eth_native_posix_rx-zethblk1.1
	options: 0x0, priority: -2 timeout: 4934
	state: suspended, entry: 0x48168c
	stack size 40, unused 0, usage 40 / 40 (100 %)

 0x1757be0 eth_native_posix_rx-zethblk1.0
	options: 0x0, priority: -2 timeout: 0
	state: suspended, entry: 0x48168c
	stack size 40, unused 0, usage 40 / 40 (100 %)

 0x1756bf8 tx_q[0]   
	options: 0x0, priority: -1 timeout: 0
	state: pending, entry: 0x47534b
	stack size 1200, unused 1160, usage 40 / 1200 (3 %)

 0x168aca0 net_mgmt  
	options: 0x0, priority: -1 timeout: 0
	state: pending, entry: 0x471852
	stack size 768, unused 728, usage 40 / 768 (5 %)

 0x1757020 tcp_work  
	options: 0x0, priority: -16 timeout: 0
	state: pending, entry: 0x48b672
	stack size 1024, unused 984, usage 40 / 1024 (3 %)

 0x1757f40 sysworkq  
	options: 0x0, priority: -1 timeout: 0
	state: pending, entry: 0x48b672
	stack size 1024, unused 984, usage 40 / 1024 (3 %)

 0x1686880 shell_uart
	options: 0x0, priority: 14 timeout: 0
	state: pending, entry: 0x45f31d
	stack size 4096, unused 4056, usage 40 / 4096 (0 %)

 0x1757ce0 idle      
	options: 0x1, priority: 15 timeout: 0
	state: , entry: 0x48ab82
	stack size 256, unused 216, usage 40 / 256 (15 %)

 0x1757de0 main      
	options: 0x1, priority: -2 timeout: 473600
	state: pending, entry: 0x48a175
	stack size 2048, unused 2008, usage 40 / 2048 (1 %)