Can Pthreads Guarantee Exclusive CPU Assignment for Each Thread?

[noelloen]

Hi,

First question is:
I want to assign 8 threads to 8 processors (must one to one), when I initialize the thread, does it guarantee that each CPU has one thread?
or there can be some case such that 4 threads on one process and other 4 thread on 4 processors and 3 processors have no threads at all?

Second question is:
For instance, one processor has 4 jobs running, is it possible to shift 2 of them to other processors? using IPC stuffs? or other methods?


For the above questions, is there any reference links that I can visit?
I am new to threading. Thanks ahead to anyone answer my questions.

 

[-Job-]

In C, using Posix threads, you can use pthread_processor_bind_np() to associate a thread to a specific processor. Using cthreads it's something like cthreads_thread_alloc(..., node) where node is the processor to run on.
If you don't specify, then the thread will probably run on a processor chosen depending on the OS scheduling algorithm i would imagine.

 

[ravenprp]

Hi there,

To answer your first question, yes, when you initialize 8 threads and assign them to 8 processors, it is guaranteed that each CPU will have one thread. This is because the POSIX pthread library implements a one-to-one mapping between threads and processors. This means that each thread is bound to a specific processor and will only run on that processor.

Regarding your second question, it is possible to shift jobs from one processor to another using interprocess communication (IPC) mechanisms. This allows for communication between different processes running on different processors. There are also other methods for distributing jobs among processors, such as task scheduling algorithms.

As for reference links, some useful resources for learning about threading and multiprocessing in general are:

- The POSIX Threads Programming tutorial: https://computing.llnl.gov/tutorials/pthreads/
- The Linux man pages for pthreads: https://linux.die.net/man/3/pthread_create
- The book "Programming with POSIX Threads" by David R. Butenhof: https://www.oreilly.com/library/view/programming-with-posix/0201633922/

I hope this helps! Good luck with your threading journey.