CONFIG_NUM_PREEMPT_PRIORITIES:

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.

Symbol:

NUM_PREEMPT_PRIORITIES
Type:

int
Value:

“15”
User value:

(no user value)
Visibility:

“y”
Is choice item:

false
Is defined:

true
Is from env.:

false
Is special:

false
Ranges:
  • [0, 128]
Prompts:
  • “Number of preemptible priorities” if MULTITHREADING (value: “y”)
Default values:
  • 15 (value: “n”)
  • Condition: (none)
  • 0 (value: “n”)
  • Condition: !MULTITHREADING (value: “n”)
Selects:

(no selects)
Reverse (select-related) dependencies:
 

(no reverse dependencies)
Additional dependencies from enclosing menus and ifs:
 

(no additional dependencies)
Locations:
  • ../kernel/Kconfig:62