CcReadAhead macro

The CcReadAhead macro performs read-ahead (also called "lazy read") on a cached file.

Syntax


VOID CcReadAhead(
  [in] PFILE_OBJECT   FileObject,
  [in] PLARGE_INTEGER FileOffset,
  [in] ULONG          Length
);

Parameters

FileObject [in]

Pointer to a file object for the cached file on which read-ahead is to be performed.

FileOffset [in]

Pointer to a variable that specifies the starting byte offset within the cached file where the last read occurred.

Length [in]

Length in bytes of the range that was last read.

Return value

None

Remarks

The CcReadAhead macro is a wrapper for CcScheduleReadAhead that calls CcScheduleReadAhead only if Length >= 256. Measurements have shown that calling CcScheduleReadAhead for smaller reads actually decreases performance.

CcReadAhead can only be called after a successful call to CcCopyRead, CcFastCopyRead, or CcMdlRead.

Requirements

Target platform

Desktop

Header

Ntifs.h (include Ntifs.h)

See also

CcCopyRead
CcFastCopyRead
CcMdlRead
CcScheduleReadAhead
CcSetAdditionalCacheAttributes
CcSetReadAheadGranularity

 

 

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