dpcsup.c File Reference

#include "ki.h"

Go to the source code of this file.

Classes
struct	_DPC_ENTRY
Defines
#define	MAXIMUM_DPC_LIST_SIZE   16
Typedefs
typedef _DPC_ENTRY	DPC_ENTRY
typedef _DPC_ENTRY *	PDPC_ENTRY
Functions
PRKTHREAD	KiQuantumEnd (VOID)
VOID	KiTimerExpiration (IN PKDPC TimerDpc, IN PVOID DeferredContext, IN PVOID SystemArgument1, IN PVOID SystemArgument2)
VOID FASTCALL	KiTimerListExpire (IN PLIST_ENTRY ExpiredListHead, IN KIRQL OldIrql)

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Define Documentation

#define MAXIMUM_DPC_LIST_SIZE   16

Definition at line 33 of file dpcsup.c. Referenced by KiTimerListExpire().

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Typedef Documentation

typedef struct _DPC_ENTRY DPC_ENTRY

typedef struct _DPC_ENTRY * PDPC_ENTRY

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Function Documentation

PRKTHREAD KiQuantumEnd (  VOID   )

Definition at line 43 of file dpcsup.c. References _KTHREAD::ApcState, _KTHREAD::BasePriority, _KPROCESS::DisableQuantum, FALSE, KeGetCurrentPrcb, KeGetCurrentThread, KiFindReadyThread(), KiLockDispatcherDatabase, KiSetPriorityThread(), KiUnlockDispatcherDatabase(), _KTHREAD::NextProcessor, NULL, _KTHREAD::Preempted, _KTHREAD::Priority, _KTHREAD::PriorityDecrement, _KAPC_STATE::Process, _KTHREAD::Quantum, Standby, _KTHREAD::State, and _KPROCESS::ThreadQuantum. : This function is called when a quantum end event occurs on the current processor. Its function is to determine whether the thread priority should be decremented and whether a redispatch of the processor should occur. Arguments: None. Return Value: The next thread to be schedule on the current processor is returned as the function value. If this value is not NULL, then the return is with the dispatcher database locked. Otherwise, the dispatcher database is unlocked. --*/ { KPRIORITY NewPriority; KIRQL OldIrql; PKPRCB Prcb; KPRIORITY Priority; PKPROCESS Process; PRKTHREAD Thread; PRKTHREAD NextThread; // // Acquire the dispatcher database lock. // Prcb = KeGetCurrentPrcb(); Thread = KeGetCurrentThread(); KiLockDispatcherDatabase(&OldIrql); // // If the quantum has expired for the current thread, then update its // quantum and priority. // if (Thread->Quantum <= 0) { // // If quantum runout is disabled for the thread's process and // the thread is running at a realtime priority, then set the // thread quantum to the highest value and do not round robin // at the thread's priority level. Otherwise, reset the thread // quantum and decay the thread's priority as appropriate. // Process = Thread->ApcState.Process; if ((Process->DisableQuantum != FALSE) && (Thread->Priority >= LOW_REALTIME_PRIORITY)) { Thread->Quantum = MAXCHAR; } else { Thread->Quantum = Process->ThreadQuantum; // // Decrement the thread's current priority if the thread is not // running in a realtime priority class and check to determine // if the processor should be redispatched. // Priority = Thread->Priority; if (Priority < LOW_REALTIME_PRIORITY) { NewPriority = Priority - Thread->PriorityDecrement - 1; if (NewPriority < Thread->BasePriority) { NewPriority = Thread->BasePriority; } Thread->PriorityDecrement = 0; } else { NewPriority = Priority; } // // If the new thread priority is different that the current thread // priority, then the thread does not run at a realtime level and // its priority should be set. Otherwise, attempt to round robin // at the current level. // if (Priority != NewPriority) { KiSetPriorityThread(Thread, NewPriority); } else { if (Prcb->NextThread == NULL) { NextThread = KiFindReadyThread(Thread->NextProcessor, Priority); if (NextThread != NULL) { NextThread->State = Standby; Prcb->NextThread = NextThread; } } else { Thread->Preempted = FALSE; } } } } // // If a thread was scheduled for execution on the current processor, // then return the address of the thread with the dispatcher database // locked. Otherwise, return NULL with the dispatcher data unlocked. // NextThread = Prcb->NextThread; if (NextThread == NULL) { KiUnlockDispatcherDatabase(OldIrql); } return NextThread; }

VOID KiTimerExpiration (  IN PKDPC  TimerDpc, IN PVOID  DeferredContext, IN PVOID  SystemArgument1, IN PVOID  SystemArgument2 )

Definition at line 217 of file dpcsup.c. References _KTIMER::DueTime, Index, KeNumberProcessors, KiLockDispatcherDatabase, KiTimerListExpire(), KiTimerTableListHead, TIMER_TABLE_SIZE, and _KTIMER::TimerListEntry. Referenced by KiInitSystem(). 00226 : 00227 00228 This function is called when the clock interupt routine discovers that 00229 a timer has expired. 00230 00231 Arguments: 00232 00233 TimerDpc - Supplies a pointer to a control object of type DPC. 00234 00235 DeferredContext - Not used. 00236 00237 SystemArgument1 - Supplies the starting timer table index value to 00238 use for the timer table scan. 00239 00240 SystemArgument2 - Not used. 00241 00242 Return Value: 00243 00244 None. 00245 00246 --*/ 00247 00248 { 00249 ULARGE_INTEGER CurrentTime; 00250 LIST_ENTRY ExpiredListHead; 00251 LONG HandLimit; 00252 LONG Index; 00253 PLIST_ENTRY ListHead; 00254 PLIST_ENTRY NextEntry; 00255 KIRQL OldIrql; 00256 PKTIMER Timer; 00257 00258 // 00259 // Acquire the dispatcher database lock and read the current interrupt 00260 // time to determine which timers have expired. 00261 // 00262 00263 KiLockDispatcherDatabase(&OldIrql); 00264 KiQueryInterruptTime((PLARGE_INTEGER)&CurrentTime); 00265 00266 // 00267 // If the timer table has not wrapped, then start with the specified 00268 // timer table index value, and scan for timer entries that have expired. 00269 // Otherwise, start with the first entry in the timer table and scan the 00270 // entire table for timer entries that have expired. 00271 // 00272 // N.B. This later condition exists when DPC processing is blocked for a 00273 // period longer than one round trip throught the timer table. 00274 // 00275 00276 HandLimit = (LONG)KiQueryLowTickCount(); 00277 if (((ULONG)(HandLimit - PtrToLong(SystemArgument1))) >= TIMER_TABLE_SIZE) { 00278 Index = - 1; 00279 HandLimit = TIMER_TABLE_SIZE - 1; 00280 00281 } else { 00282 Index = (PtrToLong(SystemArgument1) - 1) & (TIMER_TABLE_SIZE - 1); 00283 HandLimit &= (TIMER_TABLE_SIZE - 1); 00284 } 00285 00286 InitializeListHead(&ExpiredListHead); 00287 do { 00288 Index = (Index + 1) & (TIMER_TABLE_SIZE - 1); 00289 ListHead = &KiTimerTableListHead[Index]; 00290 NextEntry = ListHead->Flink; 00291 while (NextEntry != ListHead) { 00292 Timer = CONTAINING_RECORD(NextEntry, KTIMER, TimerListEntry); 00293 if (Timer->DueTime.QuadPart <= CurrentTime.QuadPart) { 00294 00295 // 00296 // The next timer in the current timer list has expired. 00297 // Remove the entry from the timer list and insert the 00298 // timer in the expired list. 00299 // 00300 00301 RemoveEntryList(&Timer->TimerListEntry); 00302 InsertTailList(&ExpiredListHead, &Timer->TimerListEntry); 00303 NextEntry = ListHead->Flink; 00304 00305 } else { 00306 break; 00307 } 00308 } 00309 00310 } while(Index != HandLimit); 00311 00312 #if DBG 00313 00314 if ((PtrToUlong(SystemArgument2) == 0) && (KeNumberProcessors == 1)) { 00315 KiCheckTimerTable(CurrentTime); 00316 } 00317 00318 #endif 00319 00320 // 00321 // Process the expired timer list. 00322 // 00323 // N.B. The following function returns with the dispatcher database 00324 // unlocked. 00325 // 00326 00327 KiTimerListExpire(&ExpiredListHead, OldIrql); 00328 return; 00329 }

VOID FASTCALL KiTimerListExpire (  IN PLIST_ENTRY  ExpiredListHead, IN KIRQL  OldIrql )

Definition at line 333 of file dpcsup.c. References _DPC_ENTRY::Context, Count, _KDPC::DeferredContext, _KDPC::DeferredRoutine, DISPATCH_LEVEL, _KTIMER::Dpc, _DPC_ENTRY::Dpc, FALSE, _KTIMER::Header, Index, KeGetCurrentPrcb, KeInsertQueueDpc(), KeLowerIrql(), KiInsertTreeTimer(), KiLockDispatcherDatabase, KiRemoveTreeTimer, KiUnlockDispatcherDatabase(), KiWaitTest(), MAXIMUM_DPC_LIST_SIZE, MAXIMUM_PROCESSORS, NULL, _KDPC::Number, _KTIMER::Period, _DPC_ENTRY::Routine, _DISPATCHER_HEADER::SignalState, TIMER_EXPIRE_INCREMENT, and _DISPATCHER_HEADER::WaitListHead. Referenced by KeSetSystemTime(), and KiTimerExpiration(). 00340 : 00341 00342 This function is called to process a list of timers that have expired. 00343 00344 N.B. This function is called with the dispatcher database locked and 00345 returns with the dispatcher database unlocked. 00346 00347 Arguments: 00348 00349 ExpiredListHead - Supplies a pointer to a list of timers that have 00350 expired. 00351 00352 OldIrql - Supplies the previous IRQL. 00353 00354 Return Value: 00355 00356 None. 00357 00358 --*/ 00359 00360 { 00361 00362 LONG Count; 00363 PKDPC Dpc; 00364 DPC_ENTRY DpcList[MAXIMUM_DPC_LIST_SIZE]; 00365 LONG Index; 00366 LARGE_INTEGER Interval; 00367 KIRQL OldIrql1; 00368 LARGE_INTEGER SystemTime; 00369 PKTIMER Timer; 00370 00371 // 00372 // Capture the timer expiration time. 00373 // 00374 00375 KiQuerySystemTime(&SystemTime); 00376 00377 // 00378 // Remove the next timer from the expired timer list, set the state of 00379 // the timer to signaled, reinsert the timer in the timer tree if it is 00380 // periodic, and optionally call the DPC routine if one is specified. 00381 // 00382 00383 RestartScan: 00384 Count = 0; 00385 while (ExpiredListHead->Flink != ExpiredListHead) { 00386 Timer = CONTAINING_RECORD(ExpiredListHead->Flink, KTIMER, TimerListEntry); 00387 KiRemoveTreeTimer(Timer); 00388 Timer->Header.SignalState = 1; 00389 if (IsListEmpty(&Timer->Header.WaitListHead) == FALSE) { 00390 KiWaitTest(Timer, TIMER_EXPIRE_INCREMENT); 00391 } 00392 00393 // 00394 // If the timer is periodic, then compute the next interval time 00395 // and reinsert the timer in the timer tree. 00396 // 00397 // N.B. Even though the timer insertion is relative, it can still 00398 // fail if the period of the timer elapses in between computing 00399 // the time and inserting the timer in the table. If this happens, 00400 // try again. 00401 // 00402 if (Timer->Period != 0) { 00403 Interval.QuadPart = Int32x32To64(Timer->Period, - 10 * 1000); 00404 while (!KiInsertTreeTimer(Timer, Interval)) { 00405 ; 00406 } 00407 } 00408 00409 if (Timer->Dpc != NULL) { 00410 Dpc = Timer->Dpc; 00411 00412 // 00413 // If the DPC is explicitly targeted to another processor, then 00414 // queue the DPC to the target processor. Otherwise, capture the 00415 // DPC parameters for execution on the current processor. 00416 // 00417 00418 #if defined(NT_UP) 00419 00420 DpcList[Count].Dpc = Dpc; 00421 DpcList[Count].Routine = Dpc->DeferredRoutine; 00422 DpcList[Count].Context = Dpc->DeferredContext; 00423 Count += 1; 00424 if (Count == MAXIMUM_DPC_LIST_SIZE) { 00425 break; 00426 } 00427 00428 #else 00429 00430 if ((Dpc->Number >= MAXIMUM_PROCESSORS) && 00431 (((ULONG)Dpc->Number - MAXIMUM_PROCESSORS) != (ULONG)KeGetCurrentProcessorNumber())) { 00432 KeInsertQueueDpc(Dpc, 00433 ULongToPtr(SystemTime.LowPart), 00434 ULongToPtr(SystemTime.HighPart)); 00435 00436 } else { 00437 DpcList[Count].Dpc = Dpc; 00438 DpcList[Count].Routine = Dpc->DeferredRoutine; 00439 DpcList[Count].Context = Dpc->DeferredContext; 00440 Count += 1; 00441 if (Count == MAXIMUM_DPC_LIST_SIZE) { 00442 break; 00443 } 00444 } 00445 00446 #endif 00447 00448 } 00449 } 00450 00451 // 00452 // Unlock the dispacher database and process DPC list entries. 00453 // 00454 00455 if (Count != 0) { 00456 KiUnlockDispatcherDatabase(DISPATCH_LEVEL); 00457 Index = 0; 00458 do { 00459 00460 #if DBG && (defined(i386) || defined(ALPHA)) 00461 00462 // 00463 // Reset the dpc tick count. If the tick count handler, 00464 // which increments this value, detects that it has crossed 00465 // a certain threshold, a breakpoint will be generated. 00466 // 00467 00468 KeGetCurrentPrcb()->DebugDpcTime = 0; 00469 #endif 00470 00471 (DpcList[Index].Routine)(DpcList[Index].Dpc, 00472 DpcList[Index].Context, 00473 ULongToPtr(SystemTime.LowPart), 00474 ULongToPtr(SystemTime.HighPart)); 00475 00476 00477 Index += 1; 00478 } while (Index < Count); 00479 00480 // 00481 // If processing of the expired timer list was terminated because 00482 // the DPC List was full, then process any remaining entries. 00483 // 00484 00485 if (Count == MAXIMUM_DPC_LIST_SIZE) { 00486 KiLockDispatcherDatabase(&OldIrql1); 00487 goto RestartScan; 00488 } 00489 00490 KeLowerIrql(OldIrql); 00491 00492 } else { 00493 KiUnlockDispatcherDatabase(OldIrql); 00494 } 00495 00496 return; 00497 } }

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