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reactos/ntoskrnl/ke/thrdschd.c

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/*
* PROJECT: ReactOS Kernel
* LICENSE: GPL - See COPYING in the top level directory
* FILE: ntoskrnl/ke/thrdschd.c
* PURPOSE: Kernel Thread Scheduler (Affinity, Priority, Scheduling)
* PROGRAMMERS: Alex Ionescu (alex.ionescu@reactos.org)
*/
/* INCLUDES ******************************************************************/
#include <ntoskrnl.h>
#define NDEBUG
#include <debug.h>
#ifdef _WIN64
# define InterlockedOrSetMember(Destination, SetMember) \
InterlockedOr64((PLONG64)Destination, SetMember);
#else
# define InterlockedOrSetMember(Destination, SetMember) \
InterlockedOr((PLONG)Destination, SetMember);
#endif
/* GLOBALS *******************************************************************/
ULONG_PTR KiIdleSummary;
ULONG_PTR KiIdleSMTSummary;
/* FUNCTIONS *****************************************************************/
PKTHREAD
FASTCALL
KiIdleSchedule(IN PKPRCB Prcb)
{
/* FIXME: TODO */
ASSERTMSG("SMP: Not yet implemented\n", FALSE);
return NULL;
}
VOID
FASTCALL
KiProcessDeferredReadyList(IN PKPRCB Prcb)
{
PSINGLE_LIST_ENTRY ListEntry;
PKTHREAD Thread;
/* Make sure there is something on the ready list */
ASSERT(Prcb->DeferredReadyListHead.Next != NULL);
/* Get the first entry and clear the list */
ListEntry = Prcb->DeferredReadyListHead.Next;
Prcb->DeferredReadyListHead.Next = NULL;
/* Start processing loop */
do
{
/* Get the thread and advance to the next entry */
Thread = CONTAINING_RECORD(ListEntry, KTHREAD, SwapListEntry);
ListEntry = ListEntry->Next;
/* Make the thread ready */
KiDeferredReadyThread(Thread);
} while (ListEntry != NULL);
/* Make sure the ready list is still empty */
ASSERT(Prcb->DeferredReadyListHead.Next == NULL);
}
VOID
FASTCALL
KiQueueReadyThread(IN PKTHREAD Thread,
IN PKPRCB Prcb)
{
/* Call the macro. We keep the API for compatibility with ASM code */
KxQueueReadyThread(Thread, Prcb);
}
VOID
FASTCALL
KiDeferredReadyThread(IN PKTHREAD Thread)
{
PKPRCB Prcb;
BOOLEAN Preempted;
ULONG Processor = 0;
KPRIORITY OldPriority;
PKTHREAD NextThread;
/* Sanity checks */
ASSERT(Thread->State == DeferredReady);
ASSERT((Thread->Priority >= 0) && (Thread->Priority <= HIGH_PRIORITY));
/* Check if we have any adjusts to do */
if (Thread->AdjustReason == AdjustBoost)
{
/* Lock the thread */
KiAcquireThreadLock(Thread);
/* Check if the priority is low enough to qualify for boosting */
if ((Thread->Priority <= Thread->AdjustIncrement) &&
(Thread->Priority < (LOW_REALTIME_PRIORITY - 3)) &&
!(Thread->DisableBoost))
{
/* Calculate the new priority based on the adjust increment */
OldPriority = min(Thread->AdjustIncrement + 1,
LOW_REALTIME_PRIORITY - 3);
/* Make sure we're not decreasing outside of the priority range */
ASSERT((Thread->PriorityDecrement >= 0) &&
(Thread->PriorityDecrement <= Thread->Priority));
/* Calculate the new priority decrement based on the boost */
Thread->PriorityDecrement += ((SCHAR)OldPriority - Thread->Priority);
/* Again verify that this decrement is valid */
ASSERT((Thread->PriorityDecrement >= 0) &&
(Thread->PriorityDecrement <= OldPriority));
/* Set the new priority */
Thread->Priority = (SCHAR)OldPriority;
}
/* We need 4 quanta, make sure we have them, then decrease by one */
if (Thread->Quantum < 4) Thread->Quantum = 4;
Thread->Quantum--;
/* Make sure the priority is still valid */
ASSERT((Thread->Priority >= 0) && (Thread->Priority <= HIGH_PRIORITY));
/* Release the lock and clear the adjust reason */
KiReleaseThreadLock(Thread);
Thread->AdjustReason = AdjustNone;
}
else if (Thread->AdjustReason == AdjustUnwait)
{
/* Acquire the thread lock and check if this is a real-time thread */
KiAcquireThreadLock(Thread);
if (Thread->Priority < LOW_REALTIME_PRIORITY)
{
/* It's not real time, but is it time critical? */
if (Thread->BasePriority >= (LOW_REALTIME_PRIORITY - 2))
{
/* It is, so simply reset its quantum */
Thread->Quantum = Thread->QuantumReset;
}
else
{
/* Has the priority been adjusted previously? */
if (!(Thread->PriorityDecrement) && (Thread->AdjustIncrement))
{
/* Yes, reset its quantum */
Thread->Quantum = Thread->QuantumReset;
}
/* Wait code already handles quantum adjustment during APCs */
if (Thread->WaitStatus != STATUS_KERNEL_APC)
{
/* Decrease the quantum by one and check if we're out */
if (--Thread->Quantum <= 0)
{
/* We are, reset the quantum and get a new priority */
Thread->Quantum = Thread->QuantumReset;
Thread->Priority = KiComputeNewPriority(Thread, 1);
}
}
}
/* Now check if we have no decrement and boosts are enabled */
if (!(Thread->PriorityDecrement) && !(Thread->DisableBoost))
{
/* Make sure we have an increment */
ASSERT(Thread->AdjustIncrement >= 0);
/* Calculate the new priority after the increment */
OldPriority = Thread->BasePriority + Thread->AdjustIncrement;
/* Check if this is a foreground process */
if (CONTAINING_RECORD(Thread->ApcState.Process, EPROCESS, Pcb)->
Vm.Flags.MemoryPriority == MEMORY_PRIORITY_FOREGROUND)
{
/* Apply the foreground boost */
OldPriority += PsPrioritySeparation;
}
/* Check if this new priority is higher */
if (OldPriority > Thread->Priority)
{
/* Make sure we don't go into the real time range */
if (OldPriority >= LOW_REALTIME_PRIORITY)
{
/* Normalize it back down one notch */
OldPriority = LOW_REALTIME_PRIORITY - 1;
}
/* Check if the priority is higher then the boosted base */
if (OldPriority > (Thread->BasePriority +
Thread->AdjustIncrement))
{
/* Setup a priority decrement to nullify the boost */
Thread->PriorityDecrement = ((SCHAR)OldPriority -
Thread->BasePriority -
Thread->AdjustIncrement);
}
/* Make sure that the priority decrement is valid */
ASSERT((Thread->PriorityDecrement >= 0) &&
(Thread->PriorityDecrement <= OldPriority));
/* Set this new priority */
Thread->Priority = (SCHAR)OldPriority;
}
}
}
else
{
/* It's a real-time thread, so just reset its quantum */
Thread->Quantum = Thread->QuantumReset;
}
/* Make sure the priority makes sense */
ASSERT((Thread->Priority >= 0) && (Thread->Priority <= HIGH_PRIORITY));
/* Release the thread lock and reset the adjust reason */
KiReleaseThreadLock(Thread);
Thread->AdjustReason = AdjustNone;
}
/* Clear thread preemption status and save current values */
Preempted = Thread->Preempted;
OldPriority = Thread->Priority;
Thread->Preempted = FALSE;
/* Queue the thread on CPU 0 and get the PRCB and lock it */
Thread->NextProcessor = 0;
Prcb = KiProcessorBlock[0];
KiAcquirePrcbLock(Prcb);
/* Check if we have an idle summary */
if (KiIdleSummary)
{
/* Clear it and set this thread as the next one */
KiIdleSummary = 0;
Thread->State = Standby;
Prcb->NextThread = Thread;
/* Unlock the PRCB and return */
KiReleasePrcbLock(Prcb);
return;
}
/* Set the CPU number */
Thread->NextProcessor = (UCHAR)Processor;
/* Get the next scheduled thread */
NextThread = Prcb->NextThread;
if (NextThread)
{
/* Sanity check */
ASSERT(NextThread->State == Standby);
/* Check if priority changed */
if (OldPriority > NextThread->Priority)
{
/* Preempt the thread */
NextThread->Preempted = TRUE;
/* Put this one as the next one */
Thread->State = Standby;
Prcb->NextThread = Thread;
/* Set it in deferred ready mode */
NextThread->State = DeferredReady;
NextThread->DeferredProcessor = Prcb->Number;
KiReleasePrcbLock(Prcb);
KiDeferredReadyThread(NextThread);
return;
}
}
else
{
/* Set the next thread as the current thread */
NextThread = Prcb->CurrentThread;
if (OldPriority > NextThread->Priority)
{
/* Preempt it if it's already running */
if (NextThread->State == Running) NextThread->Preempted = TRUE;
/* Set the thread on standby and as the next thread */
Thread->State = Standby;
Prcb->NextThread = Thread;
/* Release the lock */
KiReleasePrcbLock(Prcb);
/* Check if we're running on another CPU */
if (KeGetCurrentProcessorNumber() != Thread->NextProcessor)
{
/* We are, send an IPI */
KiIpiSend(AFFINITY_MASK(Thread->NextProcessor), IPI_DPC);
}
return;
}
}
/* Sanity check */
ASSERT((OldPriority >= 0) && (OldPriority <= HIGH_PRIORITY));
/* Set this thread as ready */
Thread->State = Ready;
Thread->WaitTime = KeTickCount.LowPart;
/* Insert this thread in the appropriate order */
Preempted ? InsertHeadList(&Prcb->DispatcherReadyListHead[OldPriority],
&Thread->WaitListEntry) :
InsertTailList(&Prcb->DispatcherReadyListHead[OldPriority],
&Thread->WaitListEntry);
/* Update the ready summary */
Prcb->ReadySummary |= PRIORITY_MASK(OldPriority);
/* Sanity check */
ASSERT(OldPriority == Thread->Priority);
/* Release the lock */
KiReleasePrcbLock(Prcb);
}
PKTHREAD
FASTCALL
KiSelectNextThread(IN PKPRCB Prcb)
{
PKTHREAD Thread;
/* Select a ready thread */
Thread = KiSelectReadyThread(0, Prcb);
if (!Thread)
{
/* Didn't find any, get the current idle thread */
Thread = Prcb->IdleThread;
/* Enable idle scheduling */
InterlockedOrSetMember(&KiIdleSummary, Prcb->SetMember);
Prcb->IdleSchedule = TRUE;
/* FIXME: SMT support */
ASSERTMSG("SMP: Not yet implemented\n", FALSE);
}
/* Sanity checks and return the thread */
ASSERT(Thread != NULL);
ASSERT((Thread->BasePriority == 0) || (Thread->Priority != 0));
return Thread;
}
LONG_PTR
FASTCALL
KiSwapThread(IN PKTHREAD CurrentThread,
IN PKPRCB Prcb)
{
BOOLEAN ApcState = FALSE;
KIRQL WaitIrql;
LONG_PTR WaitStatus;
PKTHREAD NextThread;
ASSERT(KeGetCurrentIrql() >= DISPATCH_LEVEL);
/* Acquire the PRCB lock */
KiAcquirePrcbLock(Prcb);
/* Get the next thread */
NextThread = Prcb->NextThread;
if (NextThread)
{
/* Already got a thread, set it up */
Prcb->NextThread = NULL;
Prcb->CurrentThread = NextThread;
NextThread->State = Running;
}
else
{
/* Try to find a ready thread */
NextThread = KiSelectReadyThread(0, Prcb);
if (NextThread)
{
/* Switch to it */
Prcb->CurrentThread = NextThread;
NextThread->State = Running;
}
else
{
/* Set the idle summary */
InterlockedOrSetMember(&KiIdleSummary, Prcb->SetMember);
/* Schedule the idle thread */
NextThread = Prcb->IdleThread;
Prcb->CurrentThread = NextThread;
NextThread->State = Running;
}
}
/* Sanity check and release the PRCB */
ASSERT(CurrentThread != Prcb->IdleThread);
KiReleasePrcbLock(Prcb);
/* Save the wait IRQL */
WaitIrql = CurrentThread->WaitIrql;
/* Swap contexts */
ApcState = KiSwapContext(WaitIrql, CurrentThread);
/* Get the wait status */
WaitStatus = CurrentThread->WaitStatus;
/* Check if we need to deliver APCs */
if (ApcState)
{
/* Lower to APC_LEVEL */
KeLowerIrql(APC_LEVEL);
/* Deliver APCs */
KiDeliverApc(KernelMode, NULL, NULL);
ASSERT(WaitIrql == 0);
}
/* Lower IRQL back to what it was and return the wait status */
KeLowerIrql(WaitIrql);
return WaitStatus;
}
VOID
NTAPI
KiReadyThread(IN PKTHREAD Thread)
{
IN PKPROCESS Process = Thread->ApcState.Process;
/* Check if the process is paged out */
if (Process->State != ProcessInMemory)
{
/* We don't page out processes in ROS */
ASSERT(FALSE);
}
else if (!Thread->KernelStackResident)
{
/* Increase the stack count */
ASSERT(Process->StackCount != MAXULONG_PTR);
Process->StackCount++;
/* Set the thread to transition */
ASSERT(Thread->State != Transition);
Thread->State = Transition;
/* The stack is always resident in ROS */
ASSERT(FALSE);
}
else
{
/* Insert the thread on the deferred ready list */
KiInsertDeferredReadyList(Thread);
}
}
VOID
NTAPI
KiAdjustQuantumThread(IN PKTHREAD Thread)
{
PKPRCB Prcb = KeGetCurrentPrcb();
PKTHREAD NextThread;
/* Acquire thread and PRCB lock */
KiAcquireThreadLock(Thread);
KiAcquirePrcbLock(Prcb);
/* Don't adjust for RT threads */
if ((Thread->Priority < LOW_REALTIME_PRIORITY) &&
(Thread->BasePriority < (LOW_REALTIME_PRIORITY - 2)))
{
/* Decrease Quantum by one and see if we've ran out */
if (--Thread->Quantum <= 0)
{
/* Return quantum */
Thread->Quantum = Thread->QuantumReset;
/* Calculate new Priority */
Thread->Priority = KiComputeNewPriority(Thread, 1);
/* Check if there's no next thread scheduled */
if (!Prcb->NextThread)
{
/* Select a ready thread and check if we found one */
NextThread = KiSelectReadyThread(Thread->Priority, Prcb);
if (NextThread)
{
/* Set it on standby and switch to it */
NextThread->State = Standby;
Prcb->NextThread = NextThread;
}
}
else
{
/* This thread can be preempted again */
Thread->Preempted = FALSE;
}
}
}
/* Release locks */
KiReleasePrcbLock(Prcb);
KiReleaseThreadLock(Thread);
KiExitDispatcher(Thread->WaitIrql);
}
VOID
FASTCALL
KiSetPriorityThread(IN PKTHREAD Thread,
IN KPRIORITY Priority)
{
PKPRCB Prcb;
ULONG Processor;
BOOLEAN RequestInterrupt = FALSE;
KPRIORITY OldPriority;
PKTHREAD NewThread;
ASSERT((Priority >= 0) && (Priority <= HIGH_PRIORITY));
/* Check if priority changed */
if (Thread->Priority != Priority)
{
/* Loop priority setting in case we need to start over */
for (;;)
{
/* Choose action based on thread's state */
if (Thread->State == Ready)
{
/* Make sure we're not on the ready queue */
if (!Thread->ProcessReadyQueue)
{
/* Get the PRCB for the thread and lock it */
Processor = Thread->NextProcessor;
Prcb = KiProcessorBlock[Processor];
KiAcquirePrcbLock(Prcb);
/* Make sure the thread is still ready and on this CPU */
if ((Thread->State == Ready) &&
(Thread->NextProcessor == Prcb->Number))
{
/* Sanity check */
ASSERT((Prcb->ReadySummary &
PRIORITY_MASK(Thread->Priority)));
/* Remove it from the current queue */
if (RemoveEntryList(&Thread->WaitListEntry))
{
/* Update the ready summary */
Prcb->ReadySummary ^= PRIORITY_MASK(Thread->
Priority);
}
/* Update priority */
Thread->Priority = (SCHAR)Priority;
/* Re-insert it at its current priority */
KiInsertDeferredReadyList(Thread);
/* Release the PRCB Lock */
KiReleasePrcbLock(Prcb);
}
else
{
/* Release the lock and loop again */
KiReleasePrcbLock(Prcb);
continue;
}
}
else
{
/* It's already on the ready queue, just update priority */
Thread->Priority = (SCHAR)Priority;
}
}
else if (Thread->State == Standby)
{
/* Get the PRCB for the thread and lock it */
Processor = Thread->NextProcessor;
Prcb = KiProcessorBlock[Processor];
KiAcquirePrcbLock(Prcb);
/* Check if we're still the next thread to run */
if (Thread == Prcb->NextThread)
{
/* Get the old priority and update ours */
OldPriority = Thread->Priority;
Thread->Priority = (SCHAR)Priority;
/* Check if there was a change */
if (Priority < OldPriority)
{
/* Find a new thread */
NewThread = KiSelectReadyThread(Priority + 1, Prcb);
if (NewThread)
{
/* Found a new one, set it on standby */
NewThread->State = Standby;
Prcb->NextThread = NewThread;
/* Dispatch our thread */
KiInsertDeferredReadyList(Thread);
}
}
/* Release the PRCB lock */
KiReleasePrcbLock(Prcb);
}
else
{
/* Release the lock and try again */
KiReleasePrcbLock(Prcb);
continue;
}
}
else if (Thread->State == Running)
{
/* Get the PRCB for the thread and lock it */
Processor = Thread->NextProcessor;
Prcb = KiProcessorBlock[Processor];
KiAcquirePrcbLock(Prcb);
/* Check if we're still the current thread running */
if (Thread == Prcb->CurrentThread)
{
/* Get the old priority and update ours */
OldPriority = Thread->Priority;
Thread->Priority = (SCHAR)Priority;
/* Check if there was a change and there's no new thread */
if ((Priority < OldPriority) && !(Prcb->NextThread))
{
/* Find a new thread */
NewThread = KiSelectReadyThread(Priority + 1, Prcb);
if (NewThread)
{
/* Found a new one, set it on standby */
NewThread->State = Standby;
Prcb->NextThread = NewThread;
/* Request an interrupt */
RequestInterrupt = TRUE;
}
}
/* Release the lock and check if we need an interrupt */
KiReleasePrcbLock(Prcb);
if (RequestInterrupt)
{
/* Check if we're running on another CPU */
if (KeGetCurrentProcessorNumber() != Processor)
{
/* We are, send an IPI */
KiIpiSend(AFFINITY_MASK(Processor), IPI_DPC);
}
}
}
else
{
/* Thread changed, release lock and restart */
KiReleasePrcbLock(Prcb);
continue;
}
}
else if (Thread->State == DeferredReady)
{
/* FIXME: TODO */
DPRINT1("Deferred state not yet supported\n");
ASSERT(FALSE);
}
else
{
/* Any other state, just change priority */
Thread->Priority = (SCHAR)Priority;
}
/* If we got here, then thread state was consistent, so bail out */
break;
}
}
}
KAFFINITY
FASTCALL
KiSetAffinityThread(IN PKTHREAD Thread,
IN KAFFINITY Affinity)
{
KAFFINITY OldAffinity;
/* Get the current affinity */
OldAffinity = Thread->UserAffinity;
/* Make sure that the affinity is valid */
if (((Affinity & Thread->ApcState.Process->Affinity) != (Affinity)) ||
(!Affinity))
{
/* Bugcheck the system */
KeBugCheck(INVALID_AFFINITY_SET);
}
/* Update the new affinity */
Thread->UserAffinity = Affinity;
/* Check if system affinity is disabled */
if (!Thread->SystemAffinityActive)
{
#ifdef CONFIG_SMP
/* FIXME: TODO */
DPRINT1("Affinity support disabled!\n");
#endif
}
/* Return the old affinity */
return OldAffinity;
}
//
// This macro exists because NtYieldExecution locklessly attempts to read from
// the KPRCB's ready summary, and the usual way of going through KeGetCurrentPrcb
// would require getting fs:1C first (or gs), and then doing another dereference.
// In an attempt to minimize the amount of instructions and potential race/tear
// that could happen, Windows seems to define this as a macro that directly acceses
// the ready summary through a single fs: read by going through the KPCR's PrcbData.
//
// See http://research.microsoft.com/en-us/collaboration/global/asia-pacific/
// programs/trk_case4_process-thread_management.pdf
//
// We need this per-arch because sometimes it's Prcb and sometimes PrcbData, and
// because on x86 it's FS, and on x64 it's GS (not sure what it is on ARM/PPC).
//
#ifdef _M_IX86
#define KiGetCurrentReadySummary() __readfsdword(FIELD_OFFSET(KIPCR, PrcbData.ReadySummary))
#elif _M_AMD64
#define KiGetCurrentReadySummary() __readgsdword(FIELD_OFFSET(KIPCR, Prcb.ReadySummary))
#else
#define KiGetCurrentReadySummary() KeGetCurrentPrcb()->ReadySummary
#endif
/*
* @implemented
*/
NTSTATUS
NTAPI
NtYieldExecution(VOID)
{
NTSTATUS Status;
KIRQL OldIrql;
PKPRCB Prcb;
PKTHREAD Thread, NextThread;
/* NB: No instructions (other than entry code) should preceed this line */
/* Fail if there's no ready summary */
if (!KiGetCurrentReadySummary()) return STATUS_NO_YIELD_PERFORMED;
/* Now get the current thread, set the status... */
Status = STATUS_NO_YIELD_PERFORMED;
Thread = KeGetCurrentThread();
/* Raise IRQL to synch and get the KPRCB now */
OldIrql = KeRaiseIrqlToSynchLevel();
Prcb = KeGetCurrentPrcb();
/* Now check if there's still a ready summary */
if (Prcb->ReadySummary)
{
/* Acquire thread and PRCB lock */
KiAcquireThreadLock(Thread);
KiAcquirePrcbLock(Prcb);
/* Find a new thread to run if none was selected */
if (!Prcb->NextThread) Prcb->NextThread = KiSelectReadyThread(1, Prcb);
/* Make sure we still have a next thread to schedule */
NextThread = Prcb->NextThread;
if (NextThread)
{
/* Reset quantum and recalculate priority */
Thread->Quantum = Thread->QuantumReset;
Thread->Priority = KiComputeNewPriority(Thread, 1);
/* Release the thread lock */
KiReleaseThreadLock(Thread);
/* Set context swap busy */
KiSetThreadSwapBusy(Thread);
/* Set the new thread as running */
Prcb->NextThread = NULL;
Prcb->CurrentThread = NextThread;
NextThread->State = Running;
/* Setup a yield wait and queue the thread */
Thread->WaitReason = WrYieldExecution;
KxQueueReadyThread(Thread, Prcb);
/* Make it wait at APC_LEVEL */
Thread->WaitIrql = APC_LEVEL;
/* Sanity check */
ASSERT(OldIrql <= DISPATCH_LEVEL);
/* Swap to new thread */
KiSwapContext(APC_LEVEL, Thread);
Status = STATUS_SUCCESS;
}
else
{
/* Release the PRCB and thread lock */
KiReleasePrcbLock(Prcb);
KiReleaseThreadLock(Thread);
}
}
/* Lower IRQL and return */
KeLowerIrql(OldIrql);
return Status;
}
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