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Reduced number of POSIX thread priorities from 255 to 254 to avoid conflicts

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of lowest priority with the RTEMS IDLE thread.  This was causing the lowest
priority GNAT Ada task to never run.
This commit is contained in:
Joel Sherrill
1997-04-15 18:02:18 +00:00
parent c24fef3e90
commit 6881e0cb4b
6 changed files with 30 additions and 12 deletions
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8
c/src/exec/posix/headers/priority.h
View File

@@ -15,9 +15,15 @@
* "Numericallly higher values represent higher priorities."
*
* Thus, RTEMS Core has priorities run in the opposite sense of the POSIX API.
*
* There are only 254 posix priority levels since a task at priority level
* 255 would never run because of the RTEMS idle task. This is necessary
* because GNAT maps the lowest Ada task priority to the lowest thread
* priority. The lowest priority Ada task should get to run, so there is
* a fundamental conflict with having 255 priorities.
*/
#define POSIX_SCHEDULER_MAXIMUM_PRIORITY (255)
#define POSIX_SCHEDULER_MAXIMUM_PRIORITY (254)
#define POSIX_SCHEDULER_MINIMUM_PRIORITY (1)

8
c/src/exec/posix/include/rtems/posix/priority.h
View File

@@ -15,9 +15,15 @@
* "Numericallly higher values represent higher priorities."
*
* Thus, RTEMS Core has priorities run in the opposite sense of the POSIX API.
*
* There are only 254 posix priority levels since a task at priority level
* 255 would never run because of the RTEMS idle task. This is necessary
* because GNAT maps the lowest Ada task priority to the lowest thread
* priority. The lowest priority Ada task should get to run, so there is
* a fundamental conflict with having 255 priorities.
*/
#define POSIX_SCHEDULER_MAXIMUM_PRIORITY (255)
#define POSIX_SCHEDULER_MAXIMUM_PRIORITY (254)
#define POSIX_SCHEDULER_MINIMUM_PRIORITY (1)

6
c/src/exec/posix/inline/priority.inl
View File

@@ -17,21 +17,21 @@ RTEMS_INLINE_ROUTINE boolean _POSIX_Priority_Is_valid(
int priority
)
{
return (boolean) (priority >= 1 && priority <= 255);
return (boolean) (priority >= 1 && priority <= 254);
}
RTEMS_INLINE_ROUTINE Priority_Control _POSIX_Priority_To_core(
int priority
)
{
return (Priority_Control) (256 - priority);
return (Priority_Control) (255 - priority);
}
RTEMS_INLINE_ROUTINE int _POSIX_Priority_From_core(
Priority_Control priority
)
{
return 256 - priority;
return 255 - priority;
}
#endif

6
c/src/exec/posix/inline/rtems/posix/priority.inl
View File

@@ -17,21 +17,21 @@ RTEMS_INLINE_ROUTINE boolean _POSIX_Priority_Is_valid(
int priority
)
{
return (boolean) (priority >= 1 && priority <= 255);
return (boolean) (priority >= 1 && priority <= 254);
}
RTEMS_INLINE_ROUTINE Priority_Control _POSIX_Priority_To_core(
int priority
)
{
return (Priority_Control) (256 - priority);
return (Priority_Control) (255 - priority);
}
RTEMS_INLINE_ROUTINE int _POSIX_Priority_From_core(
Priority_Control priority
)
{
return 256 - priority;
return 255 - priority;
}
#endif

8
cpukit/posix/include/rtems/posix/priority.h
View File

@@ -15,9 +15,15 @@
* "Numericallly higher values represent higher priorities."
*
* Thus, RTEMS Core has priorities run in the opposite sense of the POSIX API.
*
* There are only 254 posix priority levels since a task at priority level
* 255 would never run because of the RTEMS idle task. This is necessary
* because GNAT maps the lowest Ada task priority to the lowest thread
* priority. The lowest priority Ada task should get to run, so there is
* a fundamental conflict with having 255 priorities.
*/
#define POSIX_SCHEDULER_MAXIMUM_PRIORITY (255)
#define POSIX_SCHEDULER_MAXIMUM_PRIORITY (254)
#define POSIX_SCHEDULER_MINIMUM_PRIORITY (1)

6
cpukit/posix/inline/rtems/posix/priority.inl
View File

@@ -17,21 +17,21 @@ RTEMS_INLINE_ROUTINE boolean _POSIX_Priority_Is_valid(
int priority
)
{
return (boolean) (priority >= 1 && priority <= 255);
return (boolean) (priority >= 1 && priority <= 254);
}
RTEMS_INLINE_ROUTINE Priority_Control _POSIX_Priority_To_core(
int priority
)
{
return (Priority_Control) (256 - priority);
return (Priority_Control) (255 - priority);
}
RTEMS_INLINE_ROUTINE int _POSIX_Priority_From_core(
Priority_Control priority
)
{
return 256 - priority;
return 255 - priority;
}
#endif