DISK_PERFORMANCE

The DISK_PERFORMANCE structure provides disk performance information.

typedef struct _DISK_PERFORMANCE { 
  LARGE_INTEGER BytesRead; 
  LARGE_INTEGER BytesWritten; 
  LARGE_INTEGER ReadTime; 
  LARGE_INTEGER WriteTime; 
  LARGE_INTEGER IdleTime;
  DWORD ReadCount; 
  DWORD WriteCount; 
  DWORD QueueDepth; 
  DWORD SplitCount;
  LARGE_INTEGER QueryTime;
  DWORD StorageDeviceNumber;
  WCHAR StorageManagerName[8];
} DISK_PERFORMANCE, *PDISK_PERFORMANCE; 

Members

BytesRead

Specifies the number of bytes read.

BytesWritten

Specifies the number of bytes written.

ReadTime

Specifies the time it took to complete the read.

WriteTime

Specifies the time it took to complete the write.

IdleTime

Specifies the idle time.

ReadCount

Specifies the number of read operations.

WriteCount

Specifies the number of write operations.

QueueDepth

Specifies the depth of the queue.

SplitCount

Specifies the cumulative count of I/Os that are actually associated I/Os. An associated I/O is fragmented I/O, where multiple I/Os to the disk are required to fulfill the original logical I/O request. The most common example of such a situation is a file that is fragmented on the disk. Such multiple I/Os are counted as split I/O counts.

QueryTime

Specifies the system time stamp when the query for this structure was returned. Use this member to synchronize between the file system driver and the caller.

StorageDeviceNumber

Specifies a unique number for the device that identifies it to the storage manager indicated in the StorageManagerName member.

StorageManagerName

Specifies the name of the storage manager that controls this device. Examples of storage managers are "PhysDisk," "FTDISK," and "DMIO."

Remarks

The DeviceIoControl function receives a DISK_PERFORMANCE structure in response to an IOCTL_DISK_PERFORMANCE control code.

Requirements

  Windows NT/2000: Requires Windows NT 3.1 or later.
  Windows 95/98: Unsupported.
  Header: Declared in Winioctl.h.

See Also

Device Input and Output Overview, Device Input and Output Structures, DeviceIoControl, IOCTL_DISK_PERFORMANCE