DISK_CACHE_INFORMATION structure (ntdddisk.h)
The DISK_CACHE_INFORMATION structure is used with the IOCTL_DISK_GET_CACHE_INFORMATION request to retrieve cache information.
Syntax
typedef struct _DISK_CACHE_INFORMATION {
BOOLEAN ParametersSavable;
BOOLEAN ReadCacheEnabled;
BOOLEAN WriteCacheEnabled;
DISK_CACHE_RETENTION_PRIORITY ReadRetentionPriority;
DISK_CACHE_RETENTION_PRIORITY WriteRetentionPriority;
USHORT DisablePrefetchTransferLength;
BOOLEAN PrefetchScalar;
union {
struct {
USHORT Minimum;
USHORT Maximum;
USHORT MaximumBlocks;
} ScalarPrefetch;
struct {
USHORT Minimum;
USHORT Maximum;
} BlockPrefetch;
} DUMMYUNIONNAME;
} DISK_CACHE_INFORMATION, *PDISK_CACHE_INFORMATION;
Members
ParametersSavable
Indicates, when set to 1, that the device is capable of saving any parameters in nonvolatile storage.
ReadCacheEnabled
Indicates, when set to 1, that the read cache is enabled.
WriteCacheEnabled
Indicates, when set to 1, that the write cache is enabled.
ReadRetentionPriority
Determines the likelihood of various types of data remaining in the cache. By means of this value, for instance, data cached from a READ or WRITE operation might be given a different priority than data cached under other circumstances, such as prefetch operations. Thus a value of EqualPriority indicates that no data is held in the cache on a preferential basis. When ReadRetentionPriority is set to EqualPriority, all types of data have equal access to cache memory. On the other hand, a value of KeepPrefetchedData indicates that a preference is to be given to prefetched data while a value of KeepReadData indicates that a preference is to be given to data cached from a READ operation. For more information about the values that can be assigned to this member see the DISK_CACHE_RETENTION_PRIORITY enumeration.
WriteRetentionPriority
See discussion under ReadRetentionPriority.
DisablePrefetchTransferLength
Disables prefetching. Prefetching might be disabled whenever the number of blocks requested exceeds the value in DisablePrefetchTransferLength. When zero, prefetching is disabled no matter what the size of the block request.
PrefetchScalar
When TRUE, Indicates that ScalarPrefetch.Maximum should be used together with the transfer length to calculate the amount of data that can be prefetched. When FALSE, BlockPrefetch.Maximum will be the maximum number of disk blocks that can be prefetched.
DUMMYUNIONNAME
DUMMYUNIONNAME.ScalarPrefetch
DUMMYUNIONNAME.ScalarPrefetch.Minimum
Contains the scalar multiplier of the transfer length of the request when PrefetchScalar is TRUE. If PrefetchScalar is TRUE, the value in ScalarPrefetch.Minimum is multiplied by the transfer length to obtain the minimum amount of data that can be prefetched into the cache on a disk operation.
DUMMYUNIONNAME.ScalarPrefetch.Maximum
Contains the scalar multiplier of the transfer length of the request when PrefetchScalar is TRUE. If PrefetchScalar is TRUE, the value in ScalarPrefetch.Maximum is multiplied by the transfer length to obtain the maximum amount of data that can be prefetched into the cache on a disk operation.
DUMMYUNIONNAME.ScalarPrefetch.MaximumBlocks
Contains the maximum size, in blocks, of the transfer length.
DUMMYUNIONNAME.BlockPrefetch
DUMMYUNIONNAME.BlockPrefetch.Minimum
Contains the scalar multiplier of the transfer length of the request when PrefetchScalar is TRUE. If PrefetchScalar is TRUE, the value in ScalarPrefetch.Minimum is multiplied by the transfer length to obtain the minimum amount of data that can be prefetched into the cache on a disk operation.
DUMMYUNIONNAME.BlockPrefetch.Maximum
Contains the scalar multiplier of the transfer length of the request when PrefetchScalar is TRUE. If PrefetchScalar is TRUE, the value in ScalarPrefetch.Maximum is multiplied by the transfer length to obtain the maximum amount of data that can be prefetched into the cache on a disk operation.
Requirements
| Requirement | Value |
|---|---|
| Header | ntdddisk.h (include Ntdddisk.h) |