[Development] Thread priority on Linux - Qt 6.9.1

[Art Greenberg]

Sorry to intrude. I'm new to the list, and have joined because I have a 
question/suggestion that it looks like only the dev team can respond to.
I haven't discovered a way to search the list archives to see if my 
question has previously been answered.

I am a hobbyist. I write applications on and for Linux. Occasionally, I 
need to elevate a thread's priority for a real-time (ish) application. 
Using pthreads, its not difficult, but one does need to set the 
scheduling policy to one that permits elevated priority. The policy I 
find myself using the most is SCHED_FIFO.

I've recently started using QThread. It certainly makes launching a 
thread simple. But calling QThread::setPriority() didn't seem to work 
for me. I looked at the source for qthread_unix.cpp, and traced 
QThread::start() and QThread::setPriority(). Attempting to elevate the 
priority using using those methods fails because they use the -current- 
thread scheduling policy. One would need to change the policy prior to 
calling those methods. I do not see a (sanctioned) way to do that in
QThread.

I am able to overcome that limitation by obtaining the thread handle 
returned by QThread::currentThreadId() and using the native pthreads 
API. I am aware that this is not suggested in application code.

So, my question. Is there a way to set thread scheduling policy 
provided, such that changing the priority will work? A pointer to the Qt 
documentation would be appreciated.

If not, please consider this suggestion: add a method to QThread that 
allows setting the scheduling policy, or allows setting the scheduling 
policy and priority in a single call similar to pthread_setschedparam().

Thanks for your time.

-- 
Art Greenberg
352-363-9002
art at artg.tv