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SPDX-License-Identifier: CC-BY-SA-4.0 OR BSD-2-Clause
appl-config-option-type: integer
constraints:
set:
- 3
- 7
- 31
- 63
- 127
- 255
copyrights:
- Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)
default-value: 255
description: |
For the following schedulers
* ${.:/document-reference/scheduler-priority}, which is the default in uniprocessor
configurations and can be configured through the
${scheduler-priority:/name} configuration option,
* ${.:/document-reference/scheduler-smp-priority} which can be configured through the
${scheduler-priority-smp:/name} configuration option, and
* ${.:/document-reference/scheduler-smp-priority-affinity} which can be configured through the
${scheduler-priority-affinity-smp:/name} configuration option
this configuration option specifies the maximum numeric priority of any task
for these schedulers and one less that the number of priority levels for
these schedulers. For all other schedulers provided by RTEMS, this
configuration option has no effect.
enabled-by: true
index-entries:
- maximum priority
- number of priority levels
interface-type: appl-config-option
links:
- role: appl-config-group-member
uid: group-schedgeneral
name: CONFIGURE_MAXIMUM_PRIORITY
notes: |
The numerically greatest priority is the logically lowest priority in the
system and will thus be used by the IDLE task.
Priority zero is reserved for internal use by RTEMS and is not available to
applications.
Reducing the number of priorities through this configuration option reduces
the amount of memory allocated by the schedulers listed above. These
schedulers use a chain control structure per priority and this structure
consists of three pointers. On a 32-bit architecture, the allocated memory
is 12 bytes * (``CONFIGURE_MAXIMUM_PRIORITY`` + 1), e.g. 3072 bytes for 256
priority levels (default), 48 bytes for 4 priority levels
(``CONFIGURE_MAXIMUM_PRIORITY == 3``).
The default value is 255, because RTEMS shall support 256 priority levels to
be compliant with various standards. These priorities range from 0 to 255.
text: ''
type: interface
|
