PEXTERNAL_CACHE_CALLBACK_EX callback function (ntifs.h)
The PEXTERNAL_CACHE_CALLBACK_EX callback function is called by the cache manager (Cc) on every lazy write scan.
Syntax
PEXTERNAL_CACHE_CALLBACK_EX PexternalCacheCallbackEx;
void PexternalCacheCallbackEx(
PVOID ExternalCacheContext,
PCC_DIRTY_PAGES_INFO DirtyPagesInfo
)
{...}
Parameters
ExternalCacheContext
[in] Pointer to the context that identifies the external cache structure. This context was returned by CcRegisterExternalCacheEx.
DirtyPagesInfo
[in] Pointer to a CC_DIRTY_PAGES_INFO structure that contains information about dirty page statistics for the external cache.
Return value
None
Remarks
A client (file system) must register an external cache with Cc by calling CcRegisterExternalCacheEx before it can receive callbacks from Cc during lazy write scans.
The values in DirtyPagesInfo are provided by the Cc to the external cache client through this callback routine.
Targets (DirtyPageTarget and CleanLockedCachedPagesTarget) are for defining the upper limits. The client must strive to keep these metrics at or under their target value. When targets are exceeded, the client needs to aggressively bring down the corresponding metric.
Thresholds (DirtyPageThreshold and CleanLockedCachedPagesThreshold) define the hard upper limit that a client must not cross. The client must therefore pause all activities that could cause thresholds to be exceeded.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 11, version 24H2 |
| Header | ntifs.h |