| Age | Commit message (Collapse) | Author |
|---|
|
The _CPU_Context_Restart_self() implementations usually assume that self
context is executing.
FIXME: We have a race condition in _Thread_Start_multitasking() in case
another thread already performed scheduler operations and moved the heir
thread to another processor. The time frame for this is likely too
small to be practically relevant.
|
|
Close the thread object in _Thread_Make_zombie() so that all blocking
operations that use _Thread_Get() in the corresponding release directive
can find a terminating thread and can complete the operation.
|
|
Add a chain node to the scheduler node to decouple the thread and
scheduler nodes. It is now possible to enqueue a thread in a thread
wait queue and use its scheduler node at the same for other threads,
e.g. a resouce owner.
|
|
This reduces the API to the minimum data structures to maximize the
re-usability.
|
|
Add Thread_Scheduler_control to collect scheduler related fields of the
TCB.
|
|
Remove the scheduler parameter from most high level scheduler operations
like
- _Scheduler_Block(),
- _Scheduler_Unblock(),
- _Scheduler_Change_priority(),
- _Scheduler_Update_priority(),
- _Scheduler_Release_job(), and
- _Scheduler_Yield().
This simplifies the scheduler operations usage.
|
|
Add and use SCHEDULER_OPERATION_DEFAULT_GET_SET_AFFINITY.
|
|
|
|
Suppose we have two tasks A and B and two processors. Task A is about
to delete task B. Now task B calls rtems_task_wake_after(1) on the
other processor. Task B will block on the Giant lock. Task A
progresses with the task B deletion until it has to wait for
termination. Now task B obtains the Giant lock, sets its state to
STATES_DELAYING, initializes its watchdog timer and waits. Eventually
_Thread_Delay_ended() is called, but now _Thread_Get() returned NULL
since the thread is already marked as deleted. Thus task B remained
forever in the STATES_DELAYING state.
Instead of passing the thread identifier use the thread control block
directly via the watchdog user argument. This makes
_Thread_Delay_ended() also a bit more efficient.
|
|
It is used in combination with the inode number to uniquely identify a
file system node in the system.
|
|
|
|
Delete _Scheduler_priority_Get_scheduler_info().
|
|
The _Scheduler_Yield() was called by the executing thread with thread
dispatching disabled and interrupts enabled. The rtems_task_suspend()
is explicitly allowed in ISRs:
http://rtems.org/onlinedocs/doc-current/share/rtems/html/c_user/Interrupt-Manager-Directives-Allowed-from-an-ISR.html#Interrupt-Manager-Directives-Allowed-from-an-ISR
Unlike the other scheduler operations the locking was performed inside
the operation. This lead to the following race condition. Suppose a
ISR suspends the executing thread right before the yield scheduler
operation. Now the executing thread is not longer in the set of ready
threads. The typical scheduler operations did not check the thread
state and will now extract the thread again and enqueue it. This
corrupted data structures.
Add _Thread_Yield() and do the scheduler yield operation with interrupts
disabled. This has a negligible effect on the interrupt latency.
|
|
These functions are used only via the function pointers in the generic
SMP scheduler implementation. Provide them as static inline so that the
compiler can optimize more easily.
|
|
This helps to avoid untestable code for the normal SMP schedulers.
|
|
|
|
|
|
|
|
|
|
This scheduler attempts to account for needed thread migrations caused
as a side-effect of a thread state, affinity, or priority change operation.
This scheduler has its own allocate_processor handler named
_Scheduler_SMP_Allocate_processor_exact() because
_Scheduler_SMP_Allocate_processor() attempts to prevent an executing
thread from moving off its current CPU without considering affinity.
Without this, the scheduler makes all the right decisions and then
they are discarded at the end.
==Side Effects of Adding This Scheduler==
Added Thread_Control * parameter to Scheduler_SMP_Get_highest_ready type
so methods looking for the highest ready thread can filter by the processor
on which the thread blocking resides. This allows affinity to be considered.
Simple Priority SMP and Priority SMP ignore this parameter.
+ Added get_lowest_scheduled argument to _Scheduler_SMP_Enqueue_ordered().
+ Added allocate_processor argument to the following methods:
- _Scheduler_SMP_Block()
- _Scheduler_SMP_Enqueue_scheduled_ordered()
- _Scheduler_SMP_Enqueue_scheduled_ordered()
+ schedulerprioritysmpimpl.h is a new file with prototypes for methods
which were formerly static in schedulerprioritysmp.c but now need to
be public to be shared with this scheduler.
NOTE:
_Scheduler_SMP_Get_lowest_ready() appears to have a path which would
allow it to return a NULL. Previously, _Scheduler_SMP_Enqueue_ordered()
would have asserted on it. If it cannot return a NULL,
_Scheduler_SMP_Get_lowest_ready() should have an assertions.
|
|
Set the new root after the resource tree update.
|
|
Replace _Per_CPU_State_wait_for_ready_to_start_multitasking() with
_Per_CPU_State_wait_for_non_initial_state(). Implement this function.
|
|
Check that the executing thread is not NULL in _Scheduler_Tick(). It
may be NULL in case the processor has an optional scheduler assigned and
the system was not able to start the processor.
|
|
Sort enum lexicographically.
|
|
|
|
Remove rtems_current_shell_env as this is dangerous because
the env can be NULL if used outside of a valid shell with the
POSIX key to an env set up.
Clean up the usage of rtems_current_shell_env.
|
|
Rename _Scheduler_Update() to _Scheduler_Update_priority(). Add
parameter for the new thread priority to avoid direct usage of
Thread_Control::current_priority in the scheduler operation.
|
|
Replace _Scheduler_Allocate() with _Scheduler_Node_initialize(). Remove
the return status and thus the node initialization must be always
successful.
Rename _Scheduler_Free() to _Scheduler_Node_destroy().
|
|
Guest systems in paravirtualization environments run usually in user
mode. Thus it is not possible to directly access the PSR and TBR
registers. Use functions instead of inline assembler to access these
registers if RTEMS_PARAVIRT is defined.
|
|
|
|
This enables proper resource dependency tracking and as a side-effect
deadlock detection.
|
|
|
|
|
|
A resource is something that has at most one owner at a time and may
have multiple rivals in case an owner is present. The owner and rivals
are impersonated via resource nodes. A resource is represented via the
resource control structure. The resource controls and nodes are
organized as trees. It is possible to detect deadlocks via such a
resource tree. The _Resource_Iterate() function can be used to iterate
through such a resource tree starting at a top node.
|
|
Use the PTHREAD mutexes and condition variables if available. This
helps on SMP configurations to avoid the home grown condition variables
via disabled preemption.
|
|
Add and use CONFIGURE_POSIX_MUTEXES.
Add and use CONFIGURE_POSIX_CONDITION_VARIABLES.
|
|
|
|
Enabling and disabling preemption as done for single core will not work
for SMP. In the bdbuf initialization preemption handling can be avoided
in general by using pthread_once().
|
|
Do not change the scheduler with this function. Documentation. Coding
style.
|
|
Drop scheduler parameter. Coding style.
|
|
|
|
|
|
- rtems/score/assert.h: Scheduler Simulator uses glibc assert.h on GNU/Linux.
This will likely need to be adjusted more for other host compilers and
C libraries. Also disable _Assert_Not_reached() because some of these
paths do actually return to the called on the Scheduler Simulator.
- basedefs.h: Do not use noreturn attribute when on Scheduler Simulator.
Paths which context switch can return to the command interpreter on
the Scheduler Simulator.
|
|
|
|
|
|
Provide rtems_global_shell_env as a public read-only variable for
backward compatibility.
|
|
Add basic support for the Multiprocessor Resource Sharing Protocol
(MrsP).
The Multiprocessor Resource Sharing Protocol (MrsP) is defined in A.
Burns and A.J. Wellings, A Schedulability Compatible Multiprocessor
Resource Sharing Protocol - MrsP, Proceedings of the 25th Euromicro
Conference on Real-Time Systems (ECRTS 2013), July 2013. It is a
generalization of the Priority Ceiling Protocol to SMP systems. Each
MrsP semaphore uses a ceiling priority per scheduler instance. These
ceiling priorities can be specified with rtems_semaphore_set_priority().
A task obtaining or owning a MrsP semaphore will execute with the
ceiling priority for its scheduler instance as specified by the MrsP
semaphore object. Tasks waiting to get ownership of a MrsP semaphore
will not relinquish the processor voluntarily. In case the owner of a
MrsP semaphore gets preempted it can ask all tasks waiting for this
semaphore to help out and temporarily borrow the right to execute on one
of their assigned processors.
The help out feature is not implemented with this patch.
|
|
Do not use the Per_CPU_Control::started in
_SMP_Start_multitasking_on_secondary_processor() since this field may be
not up to date when a secondary processor reads it. Use the read-only
scheduler assignment instead.
Add a new fatal error SMP_FATAL_MULTITASKING_START_ON_INVALID_PROCESSOR.
This prevents out-of-bounds access.
It is currently not possible to test these fatal errors. One option
would be to fake values of the _CPU_SMP_Get_current_processor(), but
unfortunately this function is inline on some architectures.
|
|
The exit SPARC system call doesn't have a function entry
point like the others do. This is probably why people use
TA 0x0 instruction directly for shutting down the system.
|
|
|
