On Dec 8, 2013, at 8:05 PM, parmeshwr_pra...@dell.com wrote:
> Hi All,
>
> How to get UEFI scheduling information ?
There is not a scheduler, there is just an event queue.
If you look in
https://svn.code.sf.net/p/edk2/code/trunk/edk2/MdeModulePkg/Core/Dxe/Event/Timer.c,
CoreTimerTick() is called on the timer tick. You can see it get registered in
https://svn.code.sf.net/p/edk2/code/trunk/edk2/MdeModulePkg/Core/Dxe/DxeMain/DxeProtocolNotify.c
The event queues are generally processed on gBS->RestoreTpl(). See
https://svn.code.sf.net/p/edk2/code/trunk/edk2/MdeModulePkg/Core/Dxe/Event/Tpl.c
/**
Lowers the task priority to the previous value. If the new
priority unmasks events at a higher priority, they are dispatched.
@param NewTpl New, lower, task priority
**/
VOID
EFIAPI
CoreRestoreTpl (
IN EFI_TPL NewTpl
)
{
EFI_TPL OldTpl;
OldTpl = gEfiCurrentTpl;
ASSERT (NewTpl <= OldTpl);
ASSERT (VALID_TPL (NewTpl));
//
// If lowering below HIGH_LEVEL, make sure
// interrupts are enabled
//
if (OldTpl >= TPL_HIGH_LEVEL && NewTpl < TPL_HIGH_LEVEL) {
gEfiCurrentTpl = TPL_HIGH_LEVEL;
}
//
// Dispatch any pending events
//
while (((-2 << NewTpl) & gEventPending) != 0) {
gEfiCurrentTpl = (UINTN) HighBitSet64 (gEventPending);
if (gEfiCurrentTpl < TPL_HIGH_LEVEL) {
CoreSetInterruptState (TRUE);
}
CoreDispatchEventNotifies (gEfiCurrentTpl);
}
//
// Set the new value
//
gEfiCurrentTpl = NewTpl;
//
// If lowering below HIGH_LEVEL, make sure
// interrupts are enabled
//
if (gEfiCurrentTpl < TPL_HIGH_LEVEL) {
CoreSetInterruptState (TRUE);
}
}
> Is this single or multi-threaded environment ?
EFI is really an event model. I’ve found this presentation to be helpful in
explaining the difference between a thread model and an event model:
http://www.cc.gatech.edu/classes/AY2009/cs4210_fall/papers/ousterhout-threads.pdf
Thanks,
Andrew Fish------------------------------------------------------------------------------
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