Use a per-CPU thread dispatch disable level. So instead of one global
thread dispatch disable level we have now one instance per processor.
This is a major performance improvement for SMP. On non-SMP
configurations this may simplifiy the interrupt entry/exit code.
The giant lock is still present, but it is now decoupled from the thread
dispatching in _Thread_Dispatch(), _Thread_Handler(),
_Thread_Restart_self() and the interrupt entry/exit. Access to the
giant lock is now available via _Giant_Acquire() and _Giant_Release().
The giant lock is still implicitly acquired via
_Thread_Dispatch_decrement_disable_level().
The giant lock is only acquired for high-level operations in interrupt
handlers (e.g. release of a semaphore, sending of an event).
As a side-effect this change fixes the lost thread dispatch necessary
indication bug in _Thread_Dispatch().
A per-CPU thread dispatch disable level greatly simplifies the SMP
support for the interrupt entry/exit code since no spin locks have to be
acquired in this area. It is only necessary to get the current
processor index and use this to calculate the address of the own per-CPU
control. This reduces the interrupt latency considerably.
All elements for the interrupt entry/exit code are now part of the
Per_CPU_Control structure: thread dispatch disable level, ISR nest level
and thread dispatch necessary. Nothing else is required (except CPU
port specific stuff like on SPARC).
Add and use _Per_CPU_Release_all().
The context switch user extensions are invoked in _Thread_Dispatch().
This change is necessary to avoid the giant lock in _Thread_Dispatch().
Rename _Per_CPU_Lock_acquire() to _Per_CPU_ISR_disable_and_acquire().
Rename _Per_CPU_Lock_release() to _Per_CPU_Release_and_ISR_enable().
Add _Per_CPU_Acquire() and _Per_CPU_Release().
The initial region (64 bytes) of SDRAM RTEMS image is remapped
to provide overlay of the initial/ROM exceptions table.
This area cannot be used for MMU mapping table. Different correctly
aligned block has to be used for MMU table. Remapping of SDRAM
(address 0x08200000) to address 0 is supported only on 1 MB block
granularity and that is why SDRAM_VEC area has to be 1 MB aligned too
but unused part of remapped region can be freely used for other
purposes (as MMU tables).
Signed-off-by: Pavel Pisa <ppisa@pikron.com>
Use the POSIX configuration value directly. Use right type early and
avoid casts. Use proper unlimited objects API. Check workspace
allocation. Make functions static.
This patch enables unlimited model in POSIX key manger and have a decent
runtime on POSIX key searching, adding and deleting operations. Memory
overhead is lower than current implementation when the size of key and key
value becomes big.
Add context parameter to _Thread_Start_multitasking() and use this
function in rtems_smp_secondary_cpu_initialize(). This avoids
duplication of code.
Fix missing floating point context initialization in
rtems_smp_secondary_cpu_initialize(). Now performed via
_Thread_Start_multitasking().
Two issues are addressed.
1. On single processor configurations the set/get of the now/uptime
timestamps is now consistently protected by ISR disable/enable
sequences. Previously nested interrupts could observe partially written
values since 64-bit writes are not atomic on 32-bit architectures in
general. This could lead to non-monotonic uptime timestamps.
2. The TOD now/uptime maintanence is now independent of the giant lock.
This is the first step to remove the giant lock in _Thread_Dispatch().
