[ros-diffs] [fireball] 44918: Samuel Serapion - Implement ExSetTimerResolution, tested with a VirtualBox driver. - Rewrite comments in TimeRefresh lock/unlock functions.
fireball at svn.reactos.org
fireball at svn.reactos.org
Sun Jan 3 19:29:31 CET 2010
Author: fireball
Date: Sun Jan 3 19:29:30 2010
New Revision: 44918
URL: http://svn.reactos.org/svn/reactos?rev=44918&view=rev
Log:
Samuel Serapion
- Implement ExSetTimerResolution, tested with a VirtualBox driver.
- Rewrite comments in TimeRefresh lock/unlock functions.
Modified:
trunk/reactos/ntoskrnl/ex/time.c
Modified: trunk/reactos/ntoskrnl/ex/time.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/ex/time.c?rev=44918&r1=44917&r2=44918&view=diff
==============================================================================
--- trunk/reactos/ntoskrnl/ex/time.c [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/ex/time.c [iso-8859-1] Sun Jan 3 19:29:30 2010
@@ -25,33 +25,195 @@
ULONG ExpTimeZoneId;
ULONG ExpTickCountMultiplier;
ERESOURCE ExpTimeRefreshLock;
+ULONG ExpKernelResolutionCount = 0;
+ULONG ExpTimerResolutionCount = 0;
/* FUNCTIONS ****************************************************************/
+/*++
+ * @name ExAcquireTimeRefreshLock
+ *
+ * The ExReleaseTimeRefreshLock routine acquires the system-wide lock used
+ * to synchronize clock interrupt frequency changes.
+ *
+ * @param Wait
+ * If TRUE, the system will block the caller thread waiting for the lock
+ * to become available. If FALSE, the routine will fail if the lock has
+ * already been acquired.
+ *
+ * @return Boolean value indicating success or failure of the lock acquisition.
+ *
+ * @remarks None.
+ *
+ *--*/
BOOLEAN
NTAPI
-ExAcquireTimeRefreshLock(BOOLEAN Wait)
-{
- /* Simply acquire the Resource */
+ExAcquireTimeRefreshLock(
+ IN BOOLEAN Wait
+ )
+{
+ /* Block APCs */
KeEnterCriticalRegion();
+
+ /* Attempt lock acquisition */
if (!(ExAcquireResourceExclusiveLite(&ExpTimeRefreshLock, Wait)))
{
- /* We failed! */
+ /* Lock was not acquired, enable APCs and fail */
KeLeaveCriticalRegion();
return FALSE;
}
- /* Success */
+ /* Lock has been acquired */
return TRUE;
}
+/*++
+ * @name ExReleaseTimeRefreshLock
+ *
+ * The ExReleaseTimeRefreshLock routine releases the system-wide lock used
+ * to synchronize clock interrupt frequency changes.
+ *
+ * @param None.
+ *
+ * @return None.
+ *
+ * @remarks None.
+ *
+ *--*/
VOID
NTAPI
-ExReleaseTimeRefreshLock(VOID)
-{
- /* Simply release the Resource */
+ExReleaseTimeRefreshLock(
+ VOID
+ )
+{
+ /* Release the lock and re-enable APCs */
ExReleaseResourceLite(&ExpTimeRefreshLock);
KeLeaveCriticalRegion();
+}
+
+/*++
+ * @name ExSetTimerResolution
+ * @exported
+ *
+ * The KiInsertQueueApc routine modifies the frequency at which the system
+ * clock interrupts.
+ *
+ * @param DesiredTime
+ * Specifies the amount of time that should elapse between each timer
+ * interrupt, in 100-nanosecond units.
+ *
+ * This parameter is ignored if SetResolution is FALSE.
+ *
+ * @param SetResolution
+ * If TRUE, the call is a request to set the clock interrupt frequency to
+ * the value specified by DesiredTime. If FALSE, the call is a request to
+ * restore the clock interrupt frequency to the system's default value.
+ *
+ * @return New timer resolution, in 100-nanosecond ticks.
+ *
+ * @remarks (1) The clock frequency is changed only if the DesiredTime value is
+ * less than the current setting.
+ *
+ * (2) The routine just returns the current setting if the DesiredTime
+ * value is greater than what is currently set.
+ *
+ * (3) If the DesiredTime value is less than the system clock can
+ * support, the routine uses the smallest resolution the system can
+ * support, and returns that value.
+ *
+ * (4) If multiple drivers have attempted to change the clock interrupt
+ * frequency, the system will only restore the default frequency
+ * once ALL drivers have called the routine with SetResolution set
+ * to FALSE.
+ *
+ * NB. This routine synchronizes with IRP_MJ_POWER requests through the
+ * TimeRefreshLock.
+ *
+ *--*/
+ULONG
+NTAPI
+ExSetTimerResolution(IN ULONG DesiredTime,
+ IN BOOLEAN SetResolution)
+{
+ ULONG CurrentIncrement;
+
+ /* Wait for clock interrupt frequency and power requests to synchronize */
+ ExAcquireTimeRefreshLock(TRUE);
+
+ /* Obey remark 2*/
+ CurrentIncrement = KeTimeIncrement;
+
+ /* Check the type of operation this is */
+ if (SetResolution)
+ {
+ /*
+ * If this is the first kernel change, bump the timer resolution change
+ * count, then bump the kernel change count as well.
+ *
+ * These two variables are tracked differently since user-mode processes
+ * can also change the timer resolution through the NtSetTimerResolution
+ * system call. A per-process flag in the EPROCESS then stores the per-
+ * process change state.
+ *
+ */
+ if (!ExpKernelResolutionCount++) ExpTimerResolutionCount++;
+
+ /* Obey remark 3 */
+ if (DesiredTime < KeMinimumIncrement) DesiredTime = KeMinimumIncrement;
+
+ /* Obey remark 1 */
+ if (DesiredTime < KeTimeIncrement)
+ {
+ /* Force this thread on CPU zero, since we don't want it to drift */
+ KeSetSystemAffinityThread(1);
+
+ /* Now call the platform driver (HAL) to make the change */
+ CurrentIncrement = HalSetTimeIncrement(DesiredTime);
+
+ /* Put the thread back to its original affinity */
+ KeRevertToUserAffinityThread();
+
+ /* Finally, keep track of the new value in the kernel */
+ KeTimeIncrement = CurrentIncrement;
+ }
+ }
+ else
+ {
+ /* First, make sure that a driver has actually changed the resolution */
+ if (ExpKernelResolutionCount)
+ {
+ /* Obey remark 4 */
+ if (--ExpKernelResolutionCount)
+ {
+ /*
+ * All kernel drivers have requested the original frequency to
+ * be restored, but there might still be user processes with an
+ * ongoing clock interrupt frequency change, so make sure that
+ * this isn't the case.
+ */
+ if (--ExpTimerResolutionCount)
+ {
+ /* Force this thread on one CPU so that it doesn't drift */
+ KeSetSystemAffinityThread(1);
+
+ /* Call the HAL to restore the frequency to its default */
+ CurrentIncrement = HalSetTimeIncrement(KeMaximumIncrement);
+
+ /* Put the thread back to its original affinity */
+ KeRevertToUserAffinityThread();
+
+ /* Finally, keep track of the new value in the kernel */
+ KeTimeIncrement = CurrentIncrement;
+ }
+ }
+ }
+ }
+
+ /* Release the clock interrupt frequency lock since changes are done */
+ ExReleaseTimeRefreshLock();
+
+ /* And return the current value -- which could reflect the new frequency */
+ return CurrentIncrement;
}
VOID
@@ -306,18 +468,6 @@
}
/*
- * @unimplemented
- */
-ULONG
-NTAPI
-ExSetTimerResolution(IN ULONG DesiredTime,
- IN BOOLEAN SetResolution)
-{
- UNIMPLEMENTED;
- return 0;
-}
-
-/*
* @implemented
*/
VOID
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