Individual Thread Priority Checking Using Command Line in Linux

Display pthreads priority

You can use a programmatic way.

   pthread_getschedparam(pthread_t thread, int *policy,
struct sched_param *param);

This function gives ya the scheduling parameters, in the struct sched_param you can find the scheduling priority as an integer.

Use that and print it to the screen.

For a better explanation, please check this man page:

http://www.kernel.org/doc/man-pages/online/pages/man3/pthread_setschedparam.3.html

How to change priority of specific thread (LWT) in Linux?

You can use chrt

Example:

sudo chrt -r -p 40 1502

where 40 is the priority and 1502 is the TID

second column from ps -eLo pid,tid,rtprio,ni,comm output

how to get thread scheduling policy from console

The command ps -eLfc will give you a list of threads running along with their scheduling policy under the row titled CLS. RR (Round Robin), TS (Time Sharing) are some of the scheduling policies that may be present.
If you want to start a process and mention a particular scheduling policy for its threads then you can use command chrt.

How to choose thread/process priority in real-time Linux?

What are all these sirq, irq, posixcputmr tasks? Kernel threads?

Yes, all the tasks in brackets are kernel threads.

At what priority should I make my software run?

From 2-69 for normal RT, and 90-98 for your very high priority application threads. The latter will block all IRQ handlers, so try to do as little as possible at high priority. Source

Do threads work with respect to their respective priority number?

Giving priorities is not a job for the compiler. It is the OS scheduler to schedule and give CPU time (called quantum) to threads.

The scheduler further tries to run as much threads at once as possible, based on the available number of CPUs. In today's multicore systems, more often than not more than one core are available.

If you want for a thread to wait for another one, use some synchronizing mechanism.

How are nice priorities and scheduler policies related to process (thread?) IDs in linux?

Thread IDs come from the same namespace as PIDs. This means that each thread is invididually addressable by its TID - some system calls do apply to the entire process (for example, kill) but others apply only to a single thread.

The scheduler system calls are generally in the latter class, because this allows you to give different threads within a process different scheduler attributes, which is often useful.



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