[Development] Thread priority on Linux - Qt 6.9.1

[Thiago Macieira]

On Friday, 27 June 2025 21:53:24 Central European Summer Time Art Greenberg 
wrote:
> 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.

Actually, no, that's perfectly fine. You an also get the thread's TID and use 
sched_setscheduler(2).

> 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().

Sorry, the API in question is reserved for root. Since Qt applications are 
almost always run as regular users, it would see very little use. Therefore, I 
don't think we'll add it.

For the few users who need it and know what they're doing, like you, you can 
use the pthreads or Linux-specific API. You're probably doing enough code 
reviews and static analyses anyway for your application running as root that 
this is not an undue burden.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Principal Engineer - Intel Platform & System Engineering
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