Kernal and User Threads:
=================
https://cs.uns.edu.ar/~jechaiz/sosd/clases/extras/03-LinuxThreads%20and%20NPTL.pdf
https://www.cs.cmu.edu/afs/cs/academic/class/15492-f07/www/pthreads.html
https://man.cx/pthread_setattr_default_np(3)#heading2
https://bootlin.com/doc/training/linux-kernel/linux-kernel-slides.pdf
