timer-r0drv-nt.cpp@ 98103

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1	/* $Id: timer-r0drv-nt.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */
2	/** @file
3	* IPRT - Timers, Ring-0 Driver, NT.
4	*/
5
6	/*
7	* Copyright (C) 2006-2023 Oracle and/or its affiliates.
8	*
9	* This file is part of VirtualBox base platform packages, as
10	* available from https://www.virtualbox.org.
11	*
12	* This program is free software; you can redistribute it and/or
13	* modify it under the terms of the GNU General Public License
14	* as published by the Free Software Foundation, in version 3 of the
15	* License.
16	*
17	* This program is distributed in the hope that it will be useful, but
18	* WITHOUT ANY WARRANTY; without even the implied warranty of
19	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20	* General Public License for more details.
21	*
22	* You should have received a copy of the GNU General Public License
23	* along with this program; if not, see <https://www.gnu.org/licenses>.
24	*
25	* The contents of this file may alternatively be used under the terms
26	* of the Common Development and Distribution License Version 1.0
27	* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
28	* in the VirtualBox distribution, in which case the provisions of the
29	* CDDL are applicable instead of those of the GPL.
30	*
31	* You may elect to license modified versions of this file under the
32	* terms and conditions of either the GPL or the CDDL or both.
33	*
34	* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
35	*/
36
37
38	/*********************************************************************************************************************************
39	* Header Files *
40	*********************************************************************************************************************************/
41	#include "the-nt-kernel.h"
42
43	#include <iprt/timer.h>
44	#include <iprt/mp.h>
45	#include <iprt/cpuset.h>
46	#include <iprt/err.h>
47	#include <iprt/asm.h>
48	#include <iprt/assert.h>
49	#include <iprt/mem.h>
50	#include <iprt/thread.h>
51
52	#include "internal-r0drv-nt.h"
53	#include "internal/magics.h"
54
55
56	/*********************************************************************************************************************************
57	* Defined Constants And Macros *
58	*********************************************************************************************************************************/
59	/** This seems to provide better accuracy. */
60	#define RTR0TIMER_NT_MANUAL_RE_ARM 1
61
62	#if !defined(IN_GUEST) \|\| defined(DOXYGEN_RUNNING)
63	/** This using high resolution timers introduced with windows 8.1. */
64	# define RTR0TIMER_NT_HIGH_RES 1
65	#endif
66
67
68	/*********************************************************************************************************************************
69	* Structures and Typedefs *
70	*********************************************************************************************************************************/
71	/**
72	* A sub timer structure.
73	*
74	* This is used for keeping the per-cpu tick and DPC object.
75	*/
76	typedef struct RTTIMERNTSUBTIMER
77	{
78	/** The tick counter. */
79	uint64_t iTick;
80	/** Pointer to the parent timer. */
81	PRTTIMER pParent;
82	/** Thread active executing the worker function, NIL if inactive. */
83	RTNATIVETHREAD volatile hActiveThread;
84	/** The NT DPC object. */
85	KDPC NtDpc;
86	/** Whether we failed to set the target CPU for the DPC and that this needs
87	* to be done at RTTimerStart (simple timers) or during timer callback (omni). */
88	bool fDpcNeedTargetCpuSet;
89	} RTTIMERNTSUBTIMER;
90	/** Pointer to a NT sub-timer structure. */
91	typedef RTTIMERNTSUBTIMER *PRTTIMERNTSUBTIMER;
92
93	/**
94	* The internal representation of an Linux timer handle.
95	*/
96	typedef struct RTTIMER
97	{
98	/** Magic.
99	* This is RTTIMER_MAGIC, but changes to something else before the timer
100	* is destroyed to indicate clearly that thread should exit. */
101	uint32_t volatile u32Magic;
102	/** Suspend count down for single shot omnit timers. */
103	int32_t volatile cOmniSuspendCountDown;
104	/** Flag indicating the timer is suspended. */
105	bool volatile fSuspended;
106	/** Whether the timer must run on one specific CPU or not. */
107	bool fSpecificCpu;
108	/** Whether the timer must run on all CPUs or not. */
109	bool fOmniTimer;
110	/** The CPU it must run on if fSpecificCpu is set.
111	* The master CPU for an omni-timer. */
112	RTCPUID idCpu;
113	/** Callback. */
114	PFNRTTIMER pfnTimer;
115	/** User argument. */
116	void *pvUser;
117
118	/** @name Periodic scheduling / RTTimerChangeInterval.
119	* @{ */
120	/** Spinlock protecting the u64NanoInterval, iMasterTick, uNtStartTime,
121	* uNtDueTime and (at least for updating) fSuspended. */
122	KSPIN_LOCK Spinlock;
123	/** The timer interval. 0 if one-shot. */
124	uint64_t volatile u64NanoInterval;
125	/** The the current master tick. This does not necessarily follow that of
126	* the subtimer, as RTTimerChangeInterval may cause it to reset. */
127	uint64_t volatile iMasterTick;
128	#ifdef RTR0TIMER_NT_MANUAL_RE_ARM
129	/** The desired NT time of the first tick.
130	* This is not set for one-shot timers, only periodic ones. */
131	uint64_t volatile uNtStartTime;
132	/** The current due time (absolute interrupt time).
133	* This is not set for one-shot timers, only periodic ones. */
134	uint64_t volatile uNtDueTime;
135	#endif
136	/** @} */
137
138	/** The NT timer object. */
139	KTIMER NtTimer;
140	#ifdef RTR0TIMER_NT_HIGH_RES
141	/** High resolution timer. If not NULL, this must be used instead of NtTimer. */
142	PEX_TIMER pHighResTimer;
143	#endif
144	/** The number of sub-timers. */
145	RTCPUID cSubTimers;
146	/** Sub-timers.
147	* Normally there is just one, but for RTTIMER_FLAGS_CPU_ALL this will contain
148	* an entry for all possible cpus. In that case the index will be the same as
149	* for the RTCpuSet. */
150	RTTIMERNTSUBTIMER aSubTimers[1];
151	} RTTIMER;
152
153
154	#ifdef RTR0TIMER_NT_MANUAL_RE_ARM
155
156	/**
157	* Get current NT interrupt time.
158	* @return NT interrupt time
159	*/
160	static uint64_t rtTimerNtQueryInterruptTime(void)
161	{
162	# ifdef RT_ARCH_AMD64
163	return KeQueryInterruptTime(); /* macro */
164	# else
165	if (g_pfnrtKeQueryInterruptTime)
166	return g_pfnrtKeQueryInterruptTime();
167
168	/* NT4 */
169	ULARGE_INTEGER InterruptTime;
170	do
171	{
172	InterruptTime.HighPart = ((KUSER_SHARED_DATA volatile *)SharedUserData)->InterruptTime.High1Time;
173	InterruptTime.LowPart = ((KUSER_SHARED_DATA volatile *)SharedUserData)->InterruptTime.LowPart;
174	} while (((KUSER_SHARED_DATA volatile *)SharedUserData)->InterruptTime.High2Time != (LONG)InterruptTime.HighPart);
175	return InterruptTime.QuadPart;
176	# endif
177	}
178
179	/**
180	* Get current NT interrupt time, high resolution variant.
181	* @return High resolution NT interrupt time
182	*/
183	static uint64_t rtTimerNtQueryInterruptTimeHighRes(void)
184	{
185	if (g_pfnrtKeQueryInterruptTimePrecise)
186	{
187	ULONG64 uQpcIgnored;
188	return g_pfnrtKeQueryInterruptTimePrecise(&uQpcIgnored);
189	}
190	return rtTimerNtQueryInterruptTime();
191	}
192
193	#endif /* RTR0TIMER_NT_MANUAL_RE_ARM */
194
195
196	/**
197	* Worker for rtTimerNtRearmInternval that calculates the next due time.
198	*
199	* @returns The next due time (relative, so always negative).
200	* @param uNtNow The current time.
201	* @param uNtStartTime The start time of the timer.
202	* @param iTick The next tick number (zero being @a uNtStartTime).
203	* @param cNtInterval The timer interval in NT ticks.
204	* @param cNtNegDueSaftyMargin The due time safety margin in negative NT
205	* ticks.
206	* @param cNtMinNegInterval The minium interval to use when in catchup
207	* mode, also negative NT ticks.
208	*/
209	DECLINLINE(int64_t) rtTimerNtCalcNextDueTime(uint64_t uNtNow, uint64_t uNtStartTime, uint64_t iTick, uint64_t cNtInterval,
210	int32_t const cNtNegDueSaftyMargin, int32_t const cNtMinNegInterval)
211	{
212	/* Calculate the actual time elapsed since timer start: */
213	int64_t iDueTime = uNtNow - uNtStartTime;
214	if (iDueTime < 0)
215	iDueTime = 0;
216
217	/* Now calculate the nominal time since timer start for the next tick: */
218	uint64_t const uNtNextRelStart = iTick * cNtInterval;
219
220	/* Calulate now much time we have to the next tick: */
221	iDueTime -= uNtNextRelStart;
222
223	/* If we haven't already overshot the due time, including some safety margin, we're good: */
224	if (iDueTime < cNtNegDueSaftyMargin)
225	return iDueTime;
226
227	/* Okay, we've overshot it and are in catchup mode: */
228	if (iDueTime < (int64_t)cNtInterval)
229	iDueTime = -(int64_t)(cNtInterval / 2); /* double time */
230	else if (iDueTime < (int64_t)(cNtInterval * 4))
231	iDueTime = -(int64_t)(cNtInterval / 4); /* quadruple time */
232	else
233	return cNtMinNegInterval;
234
235	/* Make sure we don't try intervals smaller than the minimum specified by the caller: */
236	if (iDueTime > cNtMinNegInterval)
237	iDueTime = cNtMinNegInterval;
238	return iDueTime;
239	}
240
241	/**
242	* Manually re-arms an internval timer.
243	*
244	* Turns out NT doesn't necessarily do a very good job at re-arming timers
245	* accurately, this is in part due to KeSetTimerEx API taking the interval in
246	* milliseconds.
247	*
248	* @param pTimer The timer.
249	* @param pMasterDpc The master timer DPC for passing to KeSetTimerEx
250	* in low-resolution mode. Ignored for high-res.
251	*/
252	static void rtTimerNtRearmInternval(PRTTIMER pTimer, PKDPC pMasterDpc)
253	{
254	#ifdef RTR0TIMER_NT_MANUAL_RE_ARM
255	Assert(pTimer->u64NanoInterval);
256
257	/*
258	* For simplicity we acquire the spinlock for the whole operation.
259	* This should be perfectly fine as it doesn't change the IRQL.
260	*/
261	Assert(KeGetCurrentIrql() >= DISPATCH_LEVEL);
262	KeAcquireSpinLockAtDpcLevel(&pTimer->Spinlock);
263
264	/*
265	* Make sure it wasn't suspended
266	*/
267	if (!ASMAtomicUoReadBool(&pTimer->fSuspended))
268	{
269	uint64_t const cNtInterval = ASMAtomicUoReadU64(&pTimer->u64NanoInterval) / 100;
270	uint64_t const uNtStartTime = ASMAtomicUoReadU64(&pTimer->uNtStartTime);
271	uint64_t const iTick = ++pTimer->iMasterTick;
272
273	/*
274	* Calculate the deadline for the next timer tick and arm the timer.
275	* We always use a relative tick, i.e. negative DueTime value. This is
276	* crucial for the the high resolution API as it will bugcheck otherwise.
277	*/
278	int64_t iDueTime;
279	uint64_t uNtNow;
280	# ifdef RTR0TIMER_NT_HIGH_RES
281	if (pTimer->pHighResTimer)
282	{
283	/* Must use highres time here. */
284	uNtNow = rtTimerNtQueryInterruptTimeHighRes();
285	iDueTime = rtTimerNtCalcNextDueTime(uNtNow, uNtStartTime, iTick, cNtInterval,
286	-100 /* 10us safety /, -2000 / 200us min interval*/);
287	g_pfnrtExSetTimer(pTimer->pHighResTimer, iDueTime, 0, NULL);
288	}
289	else
290	# endif
291	{
292	/* Expect interrupt time and timers to expire at the same time, so
293	don't use high res time api here. */
294	uNtNow = rtTimerNtQueryInterruptTime();
295	iDueTime = rtTimerNtCalcNextDueTime(uNtNow, uNtStartTime, iTick, cNtInterval,
296	-100 /* 10us safety /, -2500 / 250us min interval/); /* @todo use max interval here */
297	LARGE_INTEGER DueTime;
298	DueTime.QuadPart = iDueTime;
299	KeSetTimerEx(&pTimer->NtTimer, DueTime, 0, pMasterDpc);
300	}
301
302	pTimer->uNtDueTime = uNtNow + -iDueTime;
303	}
304
305	KeReleaseSpinLockFromDpcLevel(&pTimer->Spinlock);
306	#else
307	RT_NOREF(pTimer, iTick, pMasterDpc);
308	#endif
309	}
310
311
312	/**
313	* Common timer callback worker for the non-omni timers.
314	*
315	* @returns HRTIMER_NORESTART or HRTIMER_RESTART depending on whether it's a one-shot or interval timer.
316	* @param pTimer The timer.
317	*/
318	static void rtTimerNtSimpleCallbackWorker(PRTTIMER pTimer)
319	{
320	/*
321	* Check that we haven't been suspended before doing the callout.
322	*/
323	if ( !ASMAtomicUoReadBool(&pTimer->fSuspended)
324	&& pTimer->u32Magic == RTTIMER_MAGIC)
325	{
326	ASMAtomicWriteHandle(&pTimer->aSubTimers[0].hActiveThread, RTThreadNativeSelf());
327
328	if (!pTimer->u64NanoInterval)
329	ASMAtomicWriteBool(&pTimer->fSuspended, true);
330	uint64_t iTick = ++pTimer->aSubTimers[0].iTick;
331
332	pTimer->pfnTimer(pTimer, pTimer->pvUser, iTick);
333
334	/* We re-arm the timer after calling pfnTimer, as it may stop the timer
335	or change the interval, which would mean doing extra work. */
336	if (!pTimer->fSuspended && pTimer->u64NanoInterval)
337	rtTimerNtRearmInternval(pTimer, &pTimer->aSubTimers[0].NtDpc);
338
339	ASMAtomicWriteHandle(&pTimer->aSubTimers[0].hActiveThread, NIL_RTNATIVETHREAD);
340	}
341	}
342
343
344	/**
345	* Timer callback function for the low-resolution non-omni timers.
346	*
347	* @param pDpc Pointer to the DPC.
348	* @param pvUser Pointer to our internal timer structure.
349	* @param SystemArgument1 Some system argument.
350	* @param SystemArgument2 Some system argument.
351	*/
352	static void _stdcall rtTimerNtSimpleCallback(IN PKDPC pDpc, IN PVOID pvUser, IN PVOID SystemArgument1, IN PVOID SystemArgument2)
353	{
354	PRTTIMER pTimer = (PRTTIMER)pvUser;
355	AssertPtr(pTimer);
356	#ifdef RT_STRICT
357	if (KeGetCurrentIrql() < DISPATCH_LEVEL)
358	RTAssertMsg2Weak("rtTimerNtSimpleCallback: Irql=%d expected >=%d\n", KeGetCurrentIrql(), DISPATCH_LEVEL);
359	#endif
360
361	rtTimerNtSimpleCallbackWorker(pTimer);
362
363	RT_NOREF(pDpc, SystemArgument1, SystemArgument2);
364	}
365
366
367	#ifdef RTR0TIMER_NT_HIGH_RES
368	/**
369	* Timer callback function for the high-resolution non-omni timers.
370	*
371	* @param pExTimer The windows timer.
372	* @param pvUser Pointer to our internal timer structure.
373	*/
374	static void _stdcall rtTimerNtHighResSimpleCallback(PEX_TIMER pExTimer, void *pvUser)
375	{
376	PRTTIMER pTimer = (PRTTIMER)pvUser;
377	AssertPtr(pTimer);
378	Assert(pTimer->pHighResTimer == pExTimer);
379	# ifdef RT_STRICT
380	if (KeGetCurrentIrql() < DISPATCH_LEVEL)
381	RTAssertMsg2Weak("rtTimerNtHighResSimpleCallback: Irql=%d expected >=%d\n", KeGetCurrentIrql(), DISPATCH_LEVEL);
382	# endif
383
384	/* If we're not on the desired CPU, trigger the DPC. That will rearm the
385	timer and such. */
386	if ( !pTimer->fSpecificCpu
387	\|\| pTimer->idCpu == RTMpCpuId())
388	rtTimerNtSimpleCallbackWorker(pTimer);
389	else
390	KeInsertQueueDpc(&pTimer->aSubTimers[0].NtDpc, 0, 0);
391
392	RT_NOREF(pExTimer);
393	}
394	#endif /* RTR0TIMER_NT_HIGH_RES */
395
396
397	/**
398	* The slave DPC callback for an omni timer.
399	*
400	* @param pDpc The DPC object.
401	* @param pvUser Pointer to the sub-timer.
402	* @param SystemArgument1 Some system stuff.
403	* @param SystemArgument2 Some system stuff.
404	*/
405	static void _stdcall rtTimerNtOmniSlaveCallback(IN PKDPC pDpc, IN PVOID pvUser, IN PVOID SystemArgument1, IN PVOID SystemArgument2)
406	{
407	PRTTIMERNTSUBTIMER pSubTimer = (PRTTIMERNTSUBTIMER)pvUser;
408	PRTTIMER pTimer = pSubTimer->pParent;
409
410	AssertPtr(pTimer);
411	#ifdef RT_STRICT
412	if (KeGetCurrentIrql() < DISPATCH_LEVEL)
413	RTAssertMsg2Weak("rtTimerNtOmniSlaveCallback: Irql=%d expected >=%d\n", KeGetCurrentIrql(), DISPATCH_LEVEL);
414	int iCpuSelf = RTMpCpuIdToSetIndex(RTMpCpuId());
415	if (pSubTimer - &pTimer->aSubTimers[0] != iCpuSelf)
416	RTAssertMsg2Weak("rtTimerNtOmniSlaveCallback: iCpuSelf=%d pSubTimer=%p / %d\n", iCpuSelf, pSubTimer, pSubTimer - &pTimer->aSubTimers[0]);
417	#endif
418
419	/*
420	* Check that we haven't been suspended before doing the callout.
421	*/
422	if ( !ASMAtomicUoReadBool(&pTimer->fSuspended)
423	&& pTimer->u32Magic == RTTIMER_MAGIC)
424	{
425	ASMAtomicWriteHandle(&pSubTimer->hActiveThread, RTThreadNativeSelf());
426
427	if (!pTimer->u64NanoInterval)
428	if (ASMAtomicDecS32(&pTimer->cOmniSuspendCountDown) <= 0)
429	ASMAtomicWriteBool(&pTimer->fSuspended, true);
430
431	pTimer->pfnTimer(pTimer, pTimer->pvUser, ++pSubTimer->iTick);
432
433	ASMAtomicWriteHandle(&pSubTimer->hActiveThread, NIL_RTNATIVETHREAD);
434	}
435
436	NOREF(pDpc); NOREF(SystemArgument1); NOREF(SystemArgument2);
437	}
438
439
440	/**
441	* Called when we have an impcomplete DPC object.
442	*
443	* @returns KeInsertQueueDpc return value.
444	* @param pSubTimer The sub-timer to queue an DPC for.
445	* @param iCpu The CPU set index corresponding to that sub-timer.
446	*/
447	DECL_NO_INLINE(static, BOOLEAN) rtTimerNtOmniQueueDpcSlow(PRTTIMERNTSUBTIMER pSubTimer, int iCpu)
448	{
449	int rc = rtMpNtSetTargetProcessorDpc(&pSubTimer->NtDpc, RTMpCpuIdFromSetIndex(iCpu));
450	if (RT_SUCCESS(rc))
451	{
452	pSubTimer->fDpcNeedTargetCpuSet = false;
453	return KeInsertQueueDpc(&pSubTimer->NtDpc, 0, 0);
454	}
455	return FALSE;
456	}
457
458
459	/**
460	* Wrapper around KeInsertQueueDpc that makes sure the target CPU has been set.
461	*
462	* This is for handling deferred rtMpNtSetTargetProcessorDpc failures during
463	* creation. These errors happens for offline CPUs which probably never every
464	* will come online, as very few systems do CPU hotplugging.
465	*
466	* @returns KeInsertQueueDpc return value.
467	* @param pSubTimer The sub-timer to queue an DPC for.
468	* @param iCpu The CPU set index corresponding to that sub-timer.
469	*/
470	DECLINLINE(BOOLEAN) rtTimerNtOmniQueueDpc(PRTTIMERNTSUBTIMER pSubTimer, int iCpu)
471	{
472	if (RT_LIKELY(!pSubTimer->fDpcNeedTargetCpuSet))
473	return KeInsertQueueDpc(&pSubTimer->NtDpc, 0, 0);
474	return rtTimerNtOmniQueueDpcSlow(pSubTimer, iCpu);
475	}
476
477
478	/**
479	* Common timer callback worker for omni-timers.
480	*
481	* This is responsible for queueing the DPCs for the other CPUs and
482	* perform the callback on the CPU on which it is called.
483	*
484	* @param pTimer The timer.
485	* @param pSubTimer The sub-timer of the calling CPU.
486	* @param iCpuSelf The set index of the CPU we're running on.
487	*/
488	static void rtTimerNtOmniMasterCallbackWorker(PRTTIMER pTimer, PRTTIMERNTSUBTIMER pSubTimer, int iCpuSelf)
489	{
490	/*
491	* Check that we haven't been suspended before scheduling the other DPCs
492	* and doing the callout.
493	*/
494	if ( !ASMAtomicUoReadBool(&pTimer->fSuspended)
495	&& pTimer->u32Magic == RTTIMER_MAGIC)
496	{
497	RTCPUSET OnlineSet;
498	RTMpGetOnlineSet(&OnlineSet);
499
500	ASMAtomicWriteHandle(&pSubTimer->hActiveThread, RTThreadNativeSelf());
501
502	if (pTimer->u64NanoInterval)
503	{
504	/*
505	* Recurring timer.
506	*/
507	for (int iCpu = 0; iCpu < RTCPUSET_MAX_CPUS; iCpu++)
508	if ( RTCpuSetIsMemberByIndex(&OnlineSet, iCpu)
509	&& iCpuSelf != iCpu)
510	rtTimerNtOmniQueueDpc(&pTimer->aSubTimers[iCpu], iCpu);
511
512	pTimer->pfnTimer(pTimer, pTimer->pvUser, ++pSubTimer->iTick);
513
514	/* We re-arm the timer after calling pfnTimer, as it may stop the timer
515	or change the interval, which would mean doing extra work. */
516	if (!pTimer->fSuspended && pTimer->u64NanoInterval)
517	rtTimerNtRearmInternval(pTimer, &pSubTimer->NtDpc);
518	}
519	else
520	{
521	/*
522	* Single shot timers gets complicated wrt to fSuspended maintance.
523	*/
524	uint32_t cCpus = 0;
525	for (int iCpu = 0; iCpu < RTCPUSET_MAX_CPUS; iCpu++)
526	if (RTCpuSetIsMemberByIndex(&OnlineSet, iCpu))
527	cCpus++;
528	ASMAtomicAddS32(&pTimer->cOmniSuspendCountDown, cCpus); /** @todo this is bogus bogus bogus. The counter is only used here. */
529
530	for (int iCpu = 0; iCpu < RTCPUSET_MAX_CPUS; iCpu++)
531	if ( RTCpuSetIsMemberByIndex(&OnlineSet, iCpu)
532	&& iCpuSelf != iCpu)
533	if (!rtTimerNtOmniQueueDpc(&pTimer->aSubTimers[iCpu], iCpu))
534	ASMAtomicDecS32(&pTimer->cOmniSuspendCountDown); /* already queued and counted. */
535
536	if (ASMAtomicDecS32(&pTimer->cOmniSuspendCountDown) <= 0)
537	ASMAtomicWriteBool(&pTimer->fSuspended, true);
538
539	pTimer->pfnTimer(pTimer, pTimer->pvUser, ++pSubTimer->iTick);
540	}
541
542	ASMAtomicWriteHandle(&pSubTimer->hActiveThread, NIL_RTNATIVETHREAD);
543	}
544	}
545
546
547	/**
548	* The timer callback for an omni-timer, low-resolution.
549	*
550	* @param pDpc The DPC object.
551	* @param pvUser Pointer to the sub-timer.
552	* @param SystemArgument1 Some system stuff.
553	* @param SystemArgument2 Some system stuff.
554	*/
555	static void _stdcall rtTimerNtOmniMasterCallback(IN PKDPC pDpc, IN PVOID pvUser, IN PVOID SystemArgument1, IN PVOID SystemArgument2)
556	{
557	PRTTIMERNTSUBTIMER const pSubTimer = (PRTTIMERNTSUBTIMER)pvUser;
558	PRTTIMER const pTimer = pSubTimer->pParent;
559	RTCPUID idCpu = RTMpCpuId();
560	int const iCpuSelf = RTMpCpuIdToSetIndex(idCpu);
561
562	AssertPtr(pTimer);
563	#ifdef RT_STRICT
564	if (KeGetCurrentIrql() < DISPATCH_LEVEL)
565	RTAssertMsg2Weak("rtTimerNtOmniMasterCallback: Irql=%d expected >=%d\n", KeGetCurrentIrql(), DISPATCH_LEVEL);
566	/* We must be called on the master CPU or the tick variable goes south. */
567	if (pSubTimer - &pTimer->aSubTimers[0] != iCpuSelf)
568	RTAssertMsg2Weak("rtTimerNtOmniMasterCallback: iCpuSelf=%d pSubTimer=%p / %d\n", iCpuSelf, pSubTimer, pSubTimer - &pTimer->aSubTimers[0]);
569	if (pTimer->idCpu != idCpu)
570	RTAssertMsg2Weak("rtTimerNtOmniMasterCallback: pTimer->idCpu=%d vs idCpu=%d\n", pTimer->idCpu, idCpu);
571	#endif
572
573	rtTimerNtOmniMasterCallbackWorker(pTimer, pSubTimer, iCpuSelf);
574
575	RT_NOREF(pDpc, SystemArgument1, SystemArgument2);
576	}
577
578
579	#ifdef RTR0TIMER_NT_HIGH_RES
580	/**
581	* The timer callback for an high-resolution omni-timer.
582	*
583	* @param pExTimer The windows timer.
584	* @param pvUser Pointer to our internal timer structure.
585	*/
586	static void __stdcall rtTimerNtHighResOmniCallback(PEX_TIMER pExTimer, void *pvUser)
587	{
588	PRTTIMER const pTimer = (PRTTIMER)pvUser;
589	int const iCpuSelf = RTMpCpuIdToSetIndex(RTMpCpuId());
590	PRTTIMERNTSUBTIMER const pSubTimer = &pTimer->aSubTimers[iCpuSelf];
591
592	AssertPtr(pTimer);
593	Assert(pTimer->pHighResTimer == pExTimer);
594	# ifdef RT_STRICT
595	if (KeGetCurrentIrql() < DISPATCH_LEVEL)
596	RTAssertMsg2Weak("rtTimerNtHighResOmniCallback: Irql=%d expected >=%d\n", KeGetCurrentIrql(), DISPATCH_LEVEL);
597	# endif
598
599	rtTimerNtOmniMasterCallbackWorker(pTimer, pSubTimer, iCpuSelf);
600
601	RT_NOREF(pExTimer);
602	}
603	#endif /* RTR0TIMER_NT_HIGH_RES */
604
605
606	RTDECL(int) RTTimerStart(PRTTIMER pTimer, uint64_t u64First)
607	{
608	/*
609	* Validate.
610	*/
611	AssertPtrReturn(pTimer, VERR_INVALID_HANDLE);
612	AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, VERR_INVALID_HANDLE);
613
614	/*
615	* The operation is protected by the spinlock.
616	*/
617	KIRQL bSavedIrql;
618	KeAcquireSpinLock(&pTimer->Spinlock, &bSavedIrql);
619
620	/*
621	* Check the state.
622	*/
623	if (ASMAtomicUoReadBool(&pTimer->fSuspended))
624	{ /* likely */ }
625	else
626	{
627	KeReleaseSpinLock(&pTimer->Spinlock, bSavedIrql);
628	return VERR_TIMER_ACTIVE;
629	}
630	if ( !pTimer->fSpecificCpu
631	\|\| RTMpIsCpuOnline(pTimer->idCpu))
632	{ /* likely */ }
633	else
634	{
635	KeReleaseSpinLock(&pTimer->Spinlock, bSavedIrql);
636	return VERR_CPU_OFFLINE;
637	}
638
639	/*
640	* Lazy set the DPC target CPU if needed.
641	*/
642	if ( !pTimer->fSpecificCpu
643	\|\| !pTimer->aSubTimers[0].fDpcNeedTargetCpuSet)
644	{ /* likely */ }
645	else
646	{
647	int rc = rtMpNtSetTargetProcessorDpc(&pTimer->aSubTimers[0].NtDpc, pTimer->idCpu);
648	if (RT_FAILURE(rc))
649	{
650	KeReleaseSpinLock(&pTimer->Spinlock, bSavedIrql);
651	return rc;
652	}
653	}
654
655	/*
656	* Do the starting.
657	*/
658	#ifndef RTR0TIMER_NT_MANUAL_RE_ARM
659	/* Calculate the interval time: */
660	uint64_t u64Interval = pTimer->u64NanoInterval / 1000000; /* This is ms, believe it or not. */
661	ULONG ulInterval = (ULONG)u64Interval;
662	if (ulInterval != u64Interval)
663	ulInterval = MAXLONG;
664	else if (!ulInterval && pTimer->u64NanoInterval)
665	ulInterval = 1;
666	#endif
667
668	/* Translate u64First to a DueTime: */
669	LARGE_INTEGER DueTime;
670	DueTime.QuadPart = -(int64_t)(u64First / 100); /* Relative, NT time. */
671	if (!DueTime.QuadPart)
672	DueTime.QuadPart = -10; /* 1us */
673
674	/* Reset tick counters: */
675	unsigned cSubTimers = pTimer->fOmniTimer ? pTimer->cSubTimers : 1;
676	for (unsigned iCpu = 0; iCpu < cSubTimers; iCpu++)
677	pTimer->aSubTimers[iCpu].iTick = 0;
678	pTimer->iMasterTick = 0;
679
680	/* Update timer state: */
681	#ifdef RTR0TIMER_NT_MANUAL_RE_ARM
682	if (pTimer->u64NanoInterval > 0)
683	{
684	#ifdef RTR0TIMER_NT_HIGH_RES
685	uint64_t const uNtNow = pTimer->pHighResTimer ? rtTimerNtQueryInterruptTimeHighRes() : rtTimerNtQueryInterruptTime();
686	# else
687	uint64_t const uNtNow = rtTimerNtQueryInterruptTime();
688	# endif
689	pTimer->uNtStartTime = uNtNow + -DueTime.QuadPart;
690	pTimer->uNtDueTime = pTimer->uNtStartTime;
691	}
692	#endif
693	pTimer->cOmniSuspendCountDown = 0;
694	ASMAtomicWriteBool(&pTimer->fSuspended, false);
695
696	/*
697	* Finally start the NT timer.
698	*
699	* We do this without holding the spinlock to err on the side of
700	* caution in case ExSetTimer or KeSetTimerEx ever should have the idea
701	* of running the callback before returning.
702	*/
703	KeReleaseSpinLock(&pTimer->Spinlock, bSavedIrql);
704
705	#ifdef RTR0TIMER_NT_HIGH_RES
706	if (pTimer->pHighResTimer)
707	{
708	# ifdef RTR0TIMER_NT_MANUAL_RE_ARM
709	g_pfnrtExSetTimer(pTimer->pHighResTimer, DueTime.QuadPart, 0, NULL);
710	# else
711	g_pfnrtExSetTimer(pTimer->pHighResTimer, DueTime.QuadPart, RT_MIN(pTimer->u64NanoInterval / 100, MAXLONG), NULL);
712	# endif
713	}
714	else
715	#endif
716	{
717	PKDPC const pMasterDpc = &pTimer->aSubTimers[pTimer->fOmniTimer ? RTMpCpuIdToSetIndex(pTimer->idCpu) : 0].NtDpc;
718	#ifdef RTR0TIMER_NT_MANUAL_RE_ARM
719	KeSetTimerEx(&pTimer->NtTimer, DueTime, 0, pMasterDpc);
720	#else
721	KeSetTimerEx(&pTimer->NtTimer, DueTime, ulInterval, pMasterDpc);
722	#endif
723	}
724	return VINF_SUCCESS;
725	}
726
727
728	/**
729	* Worker function that stops an active timer.
730	*
731	* Shared by RTTimerStop and RTTimerDestroy.
732	*
733	* @param pTimer The active timer.
734	*/
735	static int rtTimerNtStopWorker(PRTTIMER pTimer)
736	{
737	/*
738	* Update the state from with the spinlock context.
739	*/
740	KIRQL bSavedIrql;
741	KeAcquireSpinLock(&pTimer->Spinlock, &bSavedIrql);
742
743	bool const fWasSuspended = ASMAtomicXchgBool(&pTimer->fSuspended, true);
744
745	KeReleaseSpinLock(&pTimer->Spinlock, bSavedIrql);
746	if (!fWasSuspended)
747	{
748	/*
749	* We should cacnel the timer and dequeue DPCs.
750	*/
751	#ifdef RTR0TIMER_NT_HIGH_RES
752	if (pTimer->pHighResTimer)
753	{
754	g_pfnrtExCancelTimer(pTimer->pHighResTimer, NULL);
755
756	/* We can skip the DPC stuff, unless this is an omni timer or for a specific CPU. */
757	if (!pTimer->fSpecificCpu && !pTimer->fOmniTimer)
758	return VINF_SUCCESS;
759	}
760	else
761	#endif
762	KeCancelTimer(&pTimer->NtTimer);
763
764	for (RTCPUID iCpu = 0; iCpu < pTimer->cSubTimers; iCpu++)
765	KeRemoveQueueDpc(&pTimer->aSubTimers[iCpu].NtDpc);
766	return VINF_SUCCESS;
767	}
768	return VERR_TIMER_SUSPENDED;
769	}
770
771
772	RTDECL(int) RTTimerStop(PRTTIMER pTimer)
773	{
774	/*
775	* Validate.
776	*/
777	AssertPtrReturn(pTimer, VERR_INVALID_HANDLE);
778	AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, VERR_INVALID_HANDLE);
779
780	/*
781	* Call the worker we share with RTTimerDestroy.
782	*/
783	return rtTimerNtStopWorker(pTimer);
784	}
785
786
787	RTDECL(int) RTTimerChangeInterval(PRTTIMER pTimer, uint64_t u64NanoInterval)
788	{
789	AssertPtrReturn(pTimer, VERR_INVALID_HANDLE);
790	AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, VERR_INVALID_HANDLE);
791
792	/*
793	* We do all the state changes while holding the spinlock.
794	*/
795	int rc = VINF_SUCCESS;
796	KIRQL bSavedIrql;
797	KeAcquireSpinLock(&pTimer->Spinlock, &bSavedIrql);
798
799	/*
800	* When the timer isn't running, this is an simple job:
801	*/
802	if (!ASMAtomicUoReadBool(&pTimer->fSuspended))
803	pTimer->u64NanoInterval = u64NanoInterval;
804	else
805	{
806	/*
807	* We only implement changing the interval in RTR0TIMER_NT_MANUAL_RE_ARM
808	* mode right now. We typically let the new interval take effect after
809	* the next timer callback, unless that's too far ahead.
810	*/
811	#ifdef RTR0TIMER_NT_MANUAL_RE_ARM
812	pTimer->u64NanoInterval = u64NanoInterval;
813	pTimer->iMasterTick = 0;
814	# ifdef RTR0TIMER_NT_HIGH_RES
815	uint64_t const uNtNow = pTimer->pHighResTimer ? rtTimerNtQueryInterruptTimeHighRes() : rtTimerNtQueryInterruptTime();
816	# else
817	uint64_t const uNtNow = rtTimerNtQueryInterruptTime();
818	# endif
819	if (uNtNow >= pTimer->uNtDueTime)
820	pTimer->uNtStartTime = uNtNow;
821	else
822	{
823	pTimer->uNtStartTime = pTimer->uNtDueTime;
824
825	/*
826	* Re-arm the timer if the next DueTime is both more than 1.25 new
827	* intervals and at least 0.5 ms ahead.
828	*/
829	uint64_t cNtToNext = pTimer->uNtDueTime - uNtNow;
830	if ( cNtToNext >= RT_NS_1MS / 2 / 100 /* 0.5 ms */
831	&& cNtToNext * 100 > u64NanoInterval + u64NanoInterval / 4)
832	{
833	pTimer->uNtStartTime = pTimer->uNtDueTime = uNtNow + u64NanoInterval / 100;
834	# ifdef RTR0TIMER_NT_HIGH_RES
835	if (pTimer->pHighResTimer)
836	g_pfnrtExSetTimer(pTimer->pHighResTimer, -(int64_t)u64NanoInterval / 100, 0, NULL);
837	else
838	# endif
839	{
840	LARGE_INTEGER DueTime;
841	DueTime.QuadPart = -(int64_t)u64NanoInterval / 100;
842	KeSetTimerEx(&pTimer->NtTimer, DueTime, 0,
843	&pTimer->aSubTimers[pTimer->fOmniTimer ? RTMpCpuIdToSetIndex(pTimer->idCpu) : 0].NtDpc);
844	}
845	}
846	}
847	#else
848	rc = VERR_NOT_SUPPORTED;
849	#endif
850	}
851
852	KeReleaseSpinLock(&pTimer->Spinlock, bSavedIrql);
853
854	return rc;
855	}
856
857
858	RTDECL(int) RTTimerDestroy(PRTTIMER pTimer)
859	{
860	/* It's ok to pass NULL pointer. */
861	if (pTimer == /NIL_RTTIMER/ NULL)
862	return VINF_SUCCESS;
863	AssertPtrReturn(pTimer, VERR_INVALID_HANDLE);
864	AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, VERR_INVALID_HANDLE);
865
866	/*
867	* We do not support destroying a timer from the callback because it is
868	* not 101% safe since we cannot flush DPCs. Solaris has the same restriction.
869	*/
870	AssertReturn(KeGetCurrentIrql() == PASSIVE_LEVEL, VERR_INVALID_CONTEXT);
871
872	/*
873	* Invalidate the timer, stop it if it's running and finally free up the memory.
874	*/
875	ASMAtomicWriteU32(&pTimer->u32Magic, ~RTTIMER_MAGIC);
876	rtTimerNtStopWorker(pTimer);
877
878	#ifdef RTR0TIMER_NT_HIGH_RES
879	/*
880	* Destroy the high-resolution timer before flushing DPCs.
881	*/
882	if (pTimer->pHighResTimer)
883	{
884	g_pfnrtExDeleteTimer(pTimer->pHighResTimer, TRUE /fCancel/, TRUE /fWait/, NULL);
885	pTimer->pHighResTimer = NULL;
886	}
887	#endif
888
889	/*
890	* Flush DPCs to be on the safe side.
891	*/
892	if (g_pfnrtNtKeFlushQueuedDpcs)
893	g_pfnrtNtKeFlushQueuedDpcs();
894
895	RTMemFree(pTimer);
896
897	return VINF_SUCCESS;
898	}
899
900
901	RTDECL(int) RTTimerCreateEx(PRTTIMER ppTimer, uint64_t u64NanoInterval, uint32_t fFlags, PFNRTTIMER pfnTimer, void pvUser)
902	{
903	*ppTimer = NULL;
904
905	/*
906	* Validate flags.
907	*/
908	if (!RTTIMER_FLAGS_ARE_VALID(fFlags))
909	return VERR_INVALID_FLAGS;
910	if ( (fFlags & RTTIMER_FLAGS_CPU_SPECIFIC)
911	&& (fFlags & RTTIMER_FLAGS_CPU_ALL) != RTTIMER_FLAGS_CPU_ALL
912	&& !RTMpIsCpuPossible(RTMpCpuIdFromSetIndex(fFlags & RTTIMER_FLAGS_CPU_MASK)))
913	return VERR_CPU_NOT_FOUND;
914
915	/*
916	* Allocate the timer handler.
917	*/
918	RTCPUID cSubTimers = 1;
919	if ((fFlags & RTTIMER_FLAGS_CPU_ALL) == RTTIMER_FLAGS_CPU_ALL)
920	{
921	cSubTimers = RTMpGetMaxCpuId() + 1;
922	Assert(cSubTimers <= RTCPUSET_MAX_CPUS); /* On Windows we have a 1:1 relationship between cpuid and set index. */
923	}
924
925	PRTTIMER pTimer = (PRTTIMER)RTMemAllocZ(RT_UOFFSETOF_DYN(RTTIMER, aSubTimers[cSubTimers]));
926	if (!pTimer)
927	return VERR_NO_MEMORY;
928
929	/*
930	* Initialize it.
931	*
932	* Note! The difference between a SynchronizationTimer and a NotificationTimer
933	* (KeInitializeTimer) is, as far as I can gather, only that the former
934	* will wake up exactly one waiting thread and the latter will wake up
935	* everyone. Since we don't do any waiting on the NtTimer, that is not
936	* relevant to us.
937	*/
938	pTimer->u32Magic = RTTIMER_MAGIC;
939	pTimer->cOmniSuspendCountDown = 0;
940	pTimer->fSuspended = true;
941	pTimer->fSpecificCpu = (fFlags & RTTIMER_FLAGS_CPU_SPECIFIC) && (fFlags & RTTIMER_FLAGS_CPU_ALL) != RTTIMER_FLAGS_CPU_ALL;
942	pTimer->fOmniTimer = (fFlags & RTTIMER_FLAGS_CPU_ALL) == RTTIMER_FLAGS_CPU_ALL;
943	pTimer->idCpu = pTimer->fSpecificCpu ? RTMpCpuIdFromSetIndex(fFlags & RTTIMER_FLAGS_CPU_MASK) : NIL_RTCPUID;
944	pTimer->cSubTimers = cSubTimers;
945	pTimer->pfnTimer = pfnTimer;
946	pTimer->pvUser = pvUser;
947	KeInitializeSpinLock(&pTimer->Spinlock);
948	pTimer->u64NanoInterval = u64NanoInterval;
949
950	int rc = VINF_SUCCESS;
951	#ifdef RTR0TIMER_NT_HIGH_RES
952	if ( (fFlags & RTTIMER_FLAGS_HIGH_RES)
953	&& RTTimerCanDoHighResolution())
954	{
955	pTimer->pHighResTimer = g_pfnrtExAllocateTimer(pTimer->fOmniTimer ? rtTimerNtHighResOmniCallback
956	: rtTimerNtHighResSimpleCallback, pTimer,
957	EX_TIMER_HIGH_RESOLUTION \| EX_TIMER_NOTIFICATION);
958	if (!pTimer->pHighResTimer)
959	rc = VERR_OUT_OF_RESOURCES;
960	}
961	else
962	#endif
963	{
964	if (g_pfnrtKeInitializeTimerEx) /** @todo just call KeInitializeTimer. */
965	g_pfnrtKeInitializeTimerEx(&pTimer->NtTimer, SynchronizationTimer);
966	else
967	KeInitializeTimer(&pTimer->NtTimer);
968	}
969	if (RT_SUCCESS(rc))
970	{
971	RTCPUSET OnlineSet;
972	RTMpGetOnlineSet(&OnlineSet);
973
974	if (pTimer->fOmniTimer)
975	{
976	/*
977	* Initialize the per-cpu "sub-timers", select the first online cpu to be
978	* the master. This ASSUMES that no cpus will ever go offline.
979	*
980	* Note! For the high-resolution scenario, all DPC callbacks are slaves as
981	* we have a dedicated timer callback, set above during allocation,
982	* and don't control which CPU it (rtTimerNtHighResOmniCallback) is
983	* called on.
984	*/
985	pTimer->iMasterTick = 0;
986	pTimer->idCpu = NIL_RTCPUID;
987	for (unsigned iCpu = 0; iCpu < cSubTimers; iCpu++)
988	{
989	pTimer->aSubTimers[iCpu].iTick = 0;
990	pTimer->aSubTimers[iCpu].pParent = pTimer;
991
992	if ( pTimer->idCpu == NIL_RTCPUID
993	&& RTCpuSetIsMemberByIndex(&OnlineSet, iCpu))
994	{
995	pTimer->idCpu = RTMpCpuIdFromSetIndex(iCpu);
996	#ifdef RTR0TIMER_NT_HIGH_RES
997	if (pTimer->pHighResTimer)
998	KeInitializeDpc(&pTimer->aSubTimers[iCpu].NtDpc, rtTimerNtOmniSlaveCallback, &pTimer->aSubTimers[iCpu]);
999	else
1000	#endif
1001	KeInitializeDpc(&pTimer->aSubTimers[iCpu].NtDpc, rtTimerNtOmniMasterCallback, &pTimer->aSubTimers[iCpu]);
1002	}
1003	else
1004	KeInitializeDpc(&pTimer->aSubTimers[iCpu].NtDpc, rtTimerNtOmniSlaveCallback, &pTimer->aSubTimers[iCpu]);
1005	if (g_pfnrtKeSetImportanceDpc)
1006	g_pfnrtKeSetImportanceDpc(&pTimer->aSubTimers[iCpu].NtDpc, HighImportance);
1007
1008	/* This does not necessarily work for offline CPUs that could potentially be onlined
1009	at runtime, so postpone it. (See troubles on testboxmem1 after r148799.) */
1010	int rc2 = rtMpNtSetTargetProcessorDpc(&pTimer->aSubTimers[iCpu].NtDpc, iCpu);
1011	if (RT_SUCCESS(rc2))
1012	pTimer->aSubTimers[0].fDpcNeedTargetCpuSet = false;
1013	else if (!RTCpuSetIsMemberByIndex(&OnlineSet, iCpu))
1014	pTimer->aSubTimers[0].fDpcNeedTargetCpuSet = true;
1015	else
1016	{
1017	rc = rc2;
1018	break;
1019	}
1020	}
1021	Assert(pTimer->idCpu != NIL_RTCPUID);
1022	}
1023	else
1024	{
1025	/*
1026	* Initialize the first "sub-timer", target the DPC on a specific processor
1027	* if requested to do so.
1028	*/
1029	pTimer->iMasterTick = 0;
1030	pTimer->aSubTimers[0].iTick = 0;
1031	pTimer->aSubTimers[0].pParent = pTimer;
1032
1033	KeInitializeDpc(&pTimer->aSubTimers[0].NtDpc, rtTimerNtSimpleCallback, pTimer);
1034	if (g_pfnrtKeSetImportanceDpc)
1035	g_pfnrtKeSetImportanceDpc(&pTimer->aSubTimers[0].NtDpc, HighImportance);
1036	if (pTimer->fSpecificCpu)
1037	{
1038	/* This does not necessarily work for offline CPUs that could potentially be onlined
1039	at runtime, so postpone it. (See troubles on testboxmem1 after r148799.) */
1040	int rc2 = rtMpNtSetTargetProcessorDpc(&pTimer->aSubTimers[0].NtDpc, pTimer->idCpu);
1041	if (RT_SUCCESS(rc2))
1042	pTimer->aSubTimers[0].fDpcNeedTargetCpuSet = false;
1043	else if (!RTCpuSetIsMember(&OnlineSet, pTimer->idCpu))
1044	pTimer->aSubTimers[0].fDpcNeedTargetCpuSet = true;
1045	else
1046	rc = rc2;
1047	}
1048	}
1049	if (RT_SUCCESS(rc))
1050	{
1051	*ppTimer = pTimer;
1052	return VINF_SUCCESS;
1053	}
1054
1055	#ifdef RTR0TIMER_NT_HIGH_RES
1056	if (pTimer->pHighResTimer)
1057	{
1058	g_pfnrtExDeleteTimer(pTimer->pHighResTimer, FALSE, FALSE, NULL);
1059	pTimer->pHighResTimer = NULL;
1060	}
1061	#endif
1062	}
1063
1064	RTMemFree(pTimer);
1065	return rc;
1066	}
1067
1068
1069	RTDECL(int) RTTimerRequestSystemGranularity(uint32_t u32Request, uint32_t *pu32Granted)
1070	{
1071	if (!g_pfnrtNtExSetTimerResolution)
1072	return VERR_NOT_SUPPORTED;
1073
1074	ULONG ulGranted = g_pfnrtNtExSetTimerResolution(u32Request / 100, TRUE);
1075	if (pu32Granted)
1076	pu32Granted = ulGranted 100; /* NT -> ns */
1077	return VINF_SUCCESS;
1078	}
1079
1080
1081	RTDECL(int) RTTimerReleaseSystemGranularity(uint32_t u32Granted)
1082	{
1083	if (!g_pfnrtNtExSetTimerResolution)
1084	return VERR_NOT_SUPPORTED;
1085
1086	g_pfnrtNtExSetTimerResolution(0 /* ignored */, FALSE);
1087	NOREF(u32Granted);
1088	return VINF_SUCCESS;
1089	}
1090
1091
1092	RTDECL(bool) RTTimerCanDoHighResolution(void)
1093	{
1094	#ifdef RTR0TIMER_NT_HIGH_RES
1095	return g_pfnrtExAllocateTimer != NULL
1096	&& g_pfnrtExDeleteTimer != NULL
1097	&& g_pfnrtExSetTimer != NULL
1098	&& g_pfnrtExCancelTimer != NULL;
1099	#else
1100	return false;
1101	#endif
1102	}
1103

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source: vbox/trunk/src/VBox/Runtime/r0drv/nt/timer-r0drv-nt.cpp@ 98103

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