ntoskrnl/mm/pager.c

   1 /* $Id$
   2  *
   3  * COPYRIGHT:    See COPYING in the top level directory
   4  * PROJECT:      ReactOS kernel
   5  * FILE:         ntoskrnl/mm/pager.c
   6  * PURPOSE:      Moves infrequently used data out of memory
   7  * PROGRAMMER:   David Welch (welch@cwcom.net)
   8  * UPDATE HISTORY:
   9  *               27/05/98: Created
  10  */
  11
  12 /* INCLUDES ****************************************************************/
  13
  14 #include <ddk/ntddk.h>
  15 #include <internal/ps.h>
  16 #include <internal/ke.h>
  17 #include <internal/mm.h>
  18
  19 #define NDEBUG
  20 #include <internal/debug.h>
  21
  22 /* GLOBALS *******************************************************************/
  23
  24 static HANDLE PagerThreadHandle;
  25 static CLIENT_ID PagerThreadId;
  26 static KEVENT PagerThreadEvent;
  27 static BOOLEAN PagerThreadShouldTerminate;
  28 static ULONG PagerThreadWorkCount;
  29
  30 /* FUNCTIONS *****************************************************************/
  31
  32 BOOLEAN
  33 MiIsPagerThread(VOID)
  34 {
  35   return(PsGetCurrentThreadId() == PagerThreadId.UniqueThread);
  36 }
  37
  38 VOID
  39 MiStartPagerThread(VOID)
  40 {
  41   ULONG WasWorking;
  42
  43   WasWorking = InterlockedIncrement(&PagerThreadWorkCount);
  44   if (WasWorking == 1)
  45     {
  46       KeSetEvent(&PagerThreadEvent, IO_NO_INCREMENT, FALSE);
  47     }
  48 }
  49
  50 VOID
  51 MiStopPagerThread(VOID)
  52 {
  53   (VOID)InterlockedDecrement(&PagerThreadWorkCount);
  54 }
  55
  56 static NTSTATUS STDCALL
  57 MmPagerThreadMain(PVOID Ignored)
  58 {
  59    NTSTATUS Status;
  60
  61    for(;;)
  62      {
  63        /* Wake for a low memory situation or a terminate request. */
  64        Status = KeWaitForSingleObject(&PagerThreadEvent,
  65                                       0,
  66                                       KernelMode,
  67                                       FALSE,
  68                                       NULL);
  69        if (!NT_SUCCESS(Status))
  70          {
  71            DbgPrint("PagerThread: Wait failed\n");
  72            KEBUGCHECK(0);
  73          }
  74        if (PagerThreadShouldTerminate)
  75          {
  76            DbgPrint("PagerThread: Terminating\n");
  77            return(STATUS_SUCCESS);
  78          }
  79        do
  80          {
  81            /* Try and make some memory available to the system. */
  82            MmRebalanceMemoryConsumers();
  83          } while(PagerThreadWorkCount > 0);
  84      }
  85 }
  86
  87 NTSTATUS MmInitPagerThread(VOID)
  88 {
  89    NTSTATUS Status;
  90
  91    PagerThreadShouldTerminate = FALSE;
  92    PagerThreadWorkCount = 0;
  93    KeInitializeEvent(&PagerThreadEvent,
  94                      SynchronizationEvent,
  95                      FALSE);
  96
  97    Status = PsCreateSystemThread(&PagerThreadHandle,
  98                                  THREAD_ALL_ACCESS,
  99                                  NULL,
 100                                  NULL,
 101                                  &PagerThreadId,
 102                                  (PKSTART_ROUTINE) MmPagerThreadMain,
 103                                  NULL);
 104    if (!NT_SUCCESS(Status))
 105      {
 106         return(Status);
 107      }
 108
 109    return(STATUS_SUCCESS);
 110 }