:orphan:

.. title:: NUM_PREEMPT_PRIORITIES

.. option:: CONFIG_NUM_PREEMPT_PRIORITIES

*Number of preemptible priorities*

Type: ``int``

Help
====

Number of preemptible priorities available in the system. Gives access
to priorities 0 to CONFIG_NUM_PREEMPT_PRIORITIES - 1.

This can be set to 0 to disable preemptible scheduling.

Each priority requires an extra 8 bytes of RAM. Each set of 32 extra
total priorities require an extra 4 bytes and add one possible
iteration to loops that search for the next thread to run.

The total number of priorities is

 NUM_COOP_PRIORITIES + NUM_PREEMPT_PRIORITIES + 1

The extra one is for the idle thread, which must run at the lowest
priority, and be the only thread at that priority.

Defaults
========

- 0 if !\ :option:`MULTITHREADING <CONFIG_MULTITHREADING>`
- 15

Kconfig definition
==================

.. highlight:: kconfig

At ``kernel/Kconfig:62``

Included via ``Kconfig:8`` → ``Kconfig.zephyr:30``

Menu path: (Top) → General Kernel Options

.. parsed-literal::

    config NUM_PREEMPT_PRIORITIES
    	int "Number of preemptible priorities" if \ :option:`MULTITHREADING <CONFIG_MULTITHREADING>`
    	range 0 128
    	default 0 if !\ :option:`MULTITHREADING <CONFIG_MULTITHREADING>`
    	default 15
    	help
    	  Number of preemptible priorities available in the system. Gives access
    	  to priorities 0 to CONFIG_NUM_PREEMPT_PRIORITIES - 1.
	  
    	  This can be set to 0 to disable preemptible scheduling.
	  
    	  Each priority requires an extra 8 bytes of RAM. Each set of 32 extra
    	  total priorities require an extra 4 bytes and add one possible
    	  iteration to loops that search for the next thread to run.
	  
    	  The total number of priorities is
	  
    	   NUM_COOP_PRIORITIES + NUM_PREEMPT_PRIORITIES + 1
	  
    	  The extra one is for the idle thread, which must run at the lowest
    	  priority, and be the only thread at that priority.

*(The 'depends on' condition includes propagated dependencies from ifs and menus.)*