lookasid.c File Reference

#include "ntrtlp.h"
#include "heap.h"
#include "heappriv.h"

Go to the source code of this file.

Defines
#define	MINIMUM_LOOKASIDE_DEPTH   4
#define	MINIMUM_ALLOCATION_THRESHOLD   25
Functions
VOID	RtlpInitializeHeapLookaside (IN PHEAP_LOOKASIDE Lookaside, IN USHORT Depth)
VOID	RtlpDeleteHeapLookaside (IN PHEAP_LOOKASIDE Lookaside)
VOID	RtlpAdjustHeapLookasideDepth (IN PHEAP_LOOKASIDE Lookaside)
PVOID	RtlpAllocateFromHeapLookaside (IN PHEAP_LOOKASIDE Lookaside)
BOOLEAN	RtlpFreeToHeapLookaside (IN PHEAP_LOOKASIDE Lookaside, IN PVOID Entry)

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Define Documentation

#define MINIMUM_ALLOCATION_THRESHOLD   25

Definition at line 36 of file rtl/lookasid.c.

#define MINIMUM_LOOKASIDE_DEPTH   4

Definition at line 30 of file rtl/lookasid.c.

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Function Documentation

VOID RtlpAdjustHeapLookasideDepth (  IN PHEAP_LOOKASIDE  Lookaside  )

Definition at line 130 of file rtl/lookasid.c. References MINIMUM_ALLOCATION_THRESHOLD, MINIMUM_LOOKASIDE_DEPTH, and USHORT. Referenced by RtlAllocateHeap(). : 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  )

Definition at line 222 of file rtl/lookasid.c. References EXCEPTION_EXECUTE_HANDLER, NULL, and RtlpInterlockedPopEntrySList(). Referenced by RtlAllocateHeap(), RtlValidateHeap(), and RtlWalkHeap(). : 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 // #if defined(_X86_) if (USER_SHARED_DATA->ProcessorFeatures[PF_COMPARE_EXCHANGE_DOUBLE]) { #endif // defined(_X86_) try { Entry = RtlpInterlockedPopEntrySList(&Lookaside->ListHead); } except (EXCEPTION_EXECUTE_HANDLER) { Entry = NULL; } if (Entry != NULL) { return Entry; } #if defined(_X86_) } #endif // defined(_X86_) Lookaside->AllocateMisses += 1; return NULL; }

VOID RtlpDeleteHeapLookaside (  IN PHEAP_LOOKASIDE  Lookaside  )

Definition at line 101 of file rtl/lookasid.c. : 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; }

BOOLEAN RtlpFreeToHeapLookaside (  IN PHEAP_LOOKASIDE  Lookaside, IN PVOID  Entry )

Definition at line 288 of file rtl/lookasid.c. References EXCEPTION_EXECUTE_HANDLER, FALSE, RtlpInterlockedPushEntrySList(), RtlpQueryDepthSList, and TRUE. Referenced by RtlFreeHeap(). : 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 defined(_X86_) if (USER_SHARED_DATA->ProcessorFeatures[PF_COMPARE_EXCHANGE_DOUBLE]) { #endif // defined(_X86_) if (RtlpQueryDepthSList(&Lookaside->ListHead) < Lookaside->Depth) { // // We need to protect ourselves from a second thread that can // cause us to fault on the push. If we do fault then we'll // just do a regular free operation // try { RtlpInterlockedPushEntrySList(&Lookaside->ListHead, (PSINGLE_LIST_ENTRY)Entry); } except (EXCEPTION_EXECUTE_HANDLER) { Lookaside->FreeMisses += 1; return FALSE; } return TRUE; } #if defined(_X86_) } #endif // defined(_X86_) Lookaside->FreeMisses += 1; return FALSE; }

VOID RtlpInitializeHeapLookaside (  IN PHEAP_LOOKASIDE  Lookaside, IN USHORT  Depth )

Definition at line 45 of file rtl/lookasid.c. References MINIMUM_LOOKASIDE_DEPTH, and RtlpInitializeSListHead. Referenced by RtlCreateHeap(). : 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. // RtlpInitializeSListHead(&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; }

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