windows-nt/Source/XPSP1/NT/base/ntos/rtl/lookasid.c

540 lines
10 KiB
C
Raw Normal View History

2020-09-26 03:20:57 -05:00
/*++
Copyright (c) 1995 Microsoft Corporation
Module Name:
lookasid.c
Abstract:
This module implements heap lookaside list function.
Author:
David N. Cutler (davec) 19-Feb-1995
Revision History:
--*/
#include "ntrtlp.h"
#include "heap.h"
#include "heappriv.h"
// begin_ntslist
#if !defined(NTSLIST_ASSERT)
#define NTSLIST_ASSERT(x) ASSERT(x)
#endif // !defined(NTSLIST_ASSERT)
#ifdef _NTSLIST_DIRECT_
#define INLINE_SLIST __inline
#define RtlInitializeSListHead _RtlInitializeSListHead
#define _RtlFirstEntrySList FirstEntrySList
PSINGLE_LIST_ENTRY
FirstEntrySList (
const SLIST_HEADER *ListHead
);
#define RtlInterlockedPopEntrySList _RtlInterlockedPopEntrySList
#define RtlInterlockedPushEntrySList _RtlInterlockedPushEntrySList
#define RtlInterlockedFlushSList _RtlInterlockedFlushSList
#define _RtlQueryDepthSList RtlpQueryDepthSList
#else
#define INLINE_SLIST
#endif // _NTSLIST_DIRECT_
// end_ntslist
//
// Define minimum allocation threshold.
//
#define MINIMUM_ALLOCATION_THRESHOLD 25
// begin_ntslist
//
// Define forward referenced function prototypes.
//
VOID
RtlpInitializeSListHead (
IN PSLIST_HEADER ListHead
);
PSINGLE_LIST_ENTRY
FASTCALL
RtlpInterlockedPopEntrySList (
IN PSLIST_HEADER ListHead
);
PSINGLE_LIST_ENTRY
FASTCALL
RtlpInterlockedPushEntrySList (
IN PSLIST_HEADER ListHead,
IN PSINGLE_LIST_ENTRY ListEntry
);
PSINGLE_LIST_ENTRY
FASTCALL
RtlpInterlockedFlushSList (
IN PSLIST_HEADER ListHead
);
USHORT
RtlpQueryDepthSList (
IN PSLIST_HEADER SListHead
);
// end_ntslist
VOID
RtlpInitializeHeapLookaside (
IN PHEAP_LOOKASIDE Lookaside,
IN USHORT Depth
)
/*++
Routine Description:
This function initializes a heap lookaside list structure
Arguments:
Lookaside - Supplies a pointer to a heap lookaside list structure.
Allocate - Supplies a pointer to an allocate function.
Free - Supplies a pointer to a free function.
HeapHandle - Supplies a pointer to the heap that backs this lookaside list
Flags - Supplies a set of heap flags.
Size - Supplies the size for the lookaside list entries.
Depth - Supplies the maximum depth of the lookaside list.
Return Value:
None.
--*/
{
//
// Initialize the lookaside list structure.
//
RtlInitializeSListHead(&Lookaside->ListHead);
Lookaside->Depth = MINIMUM_LOOKASIDE_DEPTH;
Lookaside->MaximumDepth = 256; //Depth;
Lookaside->TotalAllocates = 0;
Lookaside->AllocateMisses = 0;
Lookaside->TotalFrees = 0;
Lookaside->FreeMisses = 0;
Lookaside->LastTotalAllocates = 0;
Lookaside->LastAllocateMisses = 0;
return;
}
VOID
RtlpDeleteHeapLookaside (
IN PHEAP_LOOKASIDE Lookaside
)
/*++
Routine Description:
This function frees any entries specified by the lookaside structure.
Arguments:
Lookaside - Supplies a pointer to a heap lookaside list structure.
Return Value:
None.
--*/
{
PVOID Entry;
return;
}
VOID
RtlpAdjustHeapLookasideDepth (
IN PHEAP_LOOKASIDE Lookaside
)
/*++
Routine Description:
This function is called periodically to adjust the maximum depth of
a single heap lookaside list.
Arguments:
Lookaside - Supplies a pointer to a heap lookaside list structure.
Return Value:
None.
--*/
{
ULONG Allocates;
ULONG Misses;
//
// Compute the total number of allocations and misses for this scan
// period.
//
Allocates = Lookaside->TotalAllocates - Lookaside->LastTotalAllocates;
Lookaside->LastTotalAllocates = Lookaside->TotalAllocates;
Misses = Lookaside->AllocateMisses - Lookaside->LastAllocateMisses;
Lookaside->LastAllocateMisses = Lookaside->AllocateMisses;
//
// Compute target depth of lookaside list.
//
{
ULONG Ratio;
ULONG Target;
//
// If the allocate rate is less than the mimimum threshold, then lower
// the maximum depth of the lookaside list. Otherwise, if the miss rate
// is less than .5%, then lower the maximum depth. Otherwise, raise the
// maximum depth based on the miss rate.
//
if (Misses >= Allocates) {
Misses = Allocates;
}
if (Allocates == 0) {
Allocates = 1;
}
Ratio = (Misses * 1000) / Allocates;
Target = Lookaside->Depth;
if (Allocates < MINIMUM_ALLOCATION_THRESHOLD) {
if (Target > (MINIMUM_LOOKASIDE_DEPTH + 10)) {
Target -= 10;
} else {
Target = MINIMUM_LOOKASIDE_DEPTH;
}
} else if (Ratio < 5) {
if (Target > (MINIMUM_LOOKASIDE_DEPTH + 1)) {
Target -= 1;
} else {
Target = MINIMUM_LOOKASIDE_DEPTH;
}
} else {
Target += ((Ratio * Lookaside->MaximumDepth) / (1000 * 2)) + 5;
if (Target > Lookaside->MaximumDepth) {
Target = Lookaside->MaximumDepth;
}
}
Lookaside->Depth = (USHORT)Target;
}
return;
}
PVOID
RtlpAllocateFromHeapLookaside (
IN PHEAP_LOOKASIDE Lookaside
)
/*++
Routine Description:
This function removes (pops) the first entry from the specified
heap lookaside list.
Arguments:
Lookaside - Supplies a pointer to a paged lookaside list structure.
Return Value:
If an entry is removed from the specified lookaside list, then the
address of the entry is returned as the function value. Otherwise,
NULL is returned.
--*/
{
PVOID Entry;
Lookaside->TotalAllocates += 1;
//
// We need to protect ourselves from a second thread that can cause us
// to fault on the pop. If we do fault then we'll just do a regular pop
// operation
//
__try {
Entry = RtlpInterlockedPopEntrySList(&Lookaside->ListHead);
} __except (EXCEPTION_EXECUTE_HANDLER) {
Entry = NULL;
}
if (Entry != NULL) {
return Entry;
}
Lookaside->AllocateMisses += 1;
return NULL;
}
BOOLEAN
RtlpFreeToHeapLookaside (
IN PHEAP_LOOKASIDE Lookaside,
IN PVOID Entry
)
/*++
Routine Description:
This function inserts (pushes) the specified entry into the specified
paged lookaside list.
Arguments:
Lookaside - Supplies a pointer to a paged lookaside list structure.
Entry - Supples a pointer to the entry that is inserted in the
lookaside list.
Return Value:
BOOLEAN - TRUE if the entry was put on the lookaside list and FALSE
otherwise.
--*/
{
Lookaside->TotalFrees += 1;
if (RtlpQueryDepthSList(&Lookaside->ListHead) < Lookaside->Depth) {
RtlpInterlockedPushEntrySList(&Lookaside->ListHead,
(PSINGLE_LIST_ENTRY)Entry);
return TRUE;
}
Lookaside->FreeMisses += 1;
return FALSE;
}
// begin_ntslist
INLINE_SLIST
VOID
RtlInitializeSListHead (
IN PSLIST_HEADER SListHead
)
/*++
Routine Description:
This function initializes a sequenced singly linked listhead.
Arguments:
SListHead - Supplies a pointer to a sequenced singly linked listhead.
Return Value:
None.
--*/
{
RtlpInitializeSListHead(SListHead);
return;
}
INLINE_SLIST
PSINGLE_LIST_ENTRY
RtlInterlockedPopEntrySList (
IN PSLIST_HEADER ListHead
)
/*++
Routine Description:
This function removes an entry from the front of a sequenced singly
linked list so that access to the list is synchronized in a MP system.
If there are no entries in the list, then a value of NULL is returned.
Otherwise, the address of the entry that is removed is returned as the
function value.
Arguments:
ListHead - Supplies a pointer to the sequenced listhead from which
an entry is to be removed.
Return Value:
The address of the entry removed from the list, or NULL if the list is
empty.
--*/
{
ULONG Count;
//
// It is posible during the pop of the sequenced list that an access
// violation can occur if a stale pointer is dereferenced. This is an
// acceptable result and the operation can be retried.
//
// N.B. The count is used to distinguish the case where the list head
// itself causes the access violation and therefore no progress
// can be made by repeating the operation.
//
Count = 0;
do {
__try {
return RtlpInterlockedPopEntrySList(ListHead);
} __except (Count++ < 20 ? EXCEPTION_EXECUTE_HANDLER : EXCEPTION_CONTINUE_SEARCH) {
continue;
}
} while (TRUE);
}
INLINE_SLIST
PSINGLE_LIST_ENTRY
RtlInterlockedPushEntrySList (
IN PSLIST_HEADER ListHead,
IN PSINGLE_LIST_ENTRY ListEntry
)
/*++
Routine Description:
This function inserts an entry at the head of a sequenced singly linked
list so that access to the list is synchronized in an MP system.
Arguments:
ListHead - Supplies a pointer to the sequenced listhead into which
an entry is to be inserted.
ListEntry - Supplies a pointer to the entry to be inserted at the
head of the list.
Return Value:
The address of the previous firt entry in the list. NULL implies list
went from empty to not empty.
--*/
{
NTSLIST_ASSERT(((ULONG_PTR)ListEntry & 0x7) == 0);
return RtlpInterlockedPushEntrySList(ListHead, ListEntry);
}
INLINE_SLIST
PSINGLE_LIST_ENTRY
RtlInterlockedFlushSList (
IN PSLIST_HEADER ListHead
)
/*++
Routine Description:
This function flushes the entire list of entries on a sequenced singly
linked list so that access to the list is synchronized in a MP system.
If there are no entries in the list, then a value of NULL is returned.
Otherwise, the address of the firt entry on the list is returned as the
function value.
Arguments:
ListHead - Supplies a pointer to the sequenced listhead from which
an entry is to be removed.
Return Value:
The address of the entry removed from the list, or NULL if the list is
empty.
--*/
{
return RtlpInterlockedFlushSList(ListHead);
}
// end_ntslist
USHORT
RtlQueryDepthSList (
IN PSLIST_HEADER SListHead
)
/*++
Routine Description:
This function queries the depth of the specified SLIST.
Arguments:
SListHead - Supplies a pointer to a sequenced singly linked listhead.
Return Value:
The current depth of the specified SLIST is returned as the function
value.
--*/
{
return RtlpQueryDepthSList(SListHead);
}