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CDROM_NOMINAL_PERFORMANCE_DESCRIPTOR structure (ntddcdrm.h)

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The CDROM_NOMINAL_PERFORMANCE_DESCRIPTOR structure gives the host an approximation of logical unit performance. It is returned by the IOCTL_CDROM_GET_PERFORMANCE I/O control request when the request type is CdromPerformanceRequest and the Except field of the CDROM_PERFORMANCE_HEADER is false (0). Separate descriptors are returned for read and write performance requests. The fields in CDROM_NOMINAL_PERFORMANCE_DESCRIPTOR correspond to the similarly named fields in the "Performance Descriptor - Nominal Performance" table described in the MultiMedia Command Set - 6 (MMC-6) specification.

Syntax

typedef struct _CDROM_NOMINAL_PERFORMANCE_DESCRIPTOR {
  UCHAR StartLba[4];
  UCHAR StartPerformance[4];
  UCHAR EndLba[4];
  UCHAR EndPerformance[4];
} CDROM_NOMINAL_PERFORMANCE_DESCRIPTOR, *PCDROM_NOMINAL_PERFORMANCE_DESCRIPTOR;

Members

StartLba[4]

The StartLba field (Start LBA) contains the first logical block address of the extent described by this descriptor.

StartPerformance[4]

The StartPerformance field (Start Performance) contains the nominal logical unit performance at the Start LBA in kilobytes per second.

EndLba[4]

The EndLba field (End LBA) contains the last logical block address of the extent described by this descriptor.

EndPerformance[4]

The EndPerformance field (End Performance) contains the nominal logical unit performance at the End LBA in kilobytes per second.

Requirements

Requirement Value
Header ntddcdrm.h (include Ntddcdrm.h)

See also

CDROM_PERFORMANCE_HEADER

IOCTL_CDROM_GET_PERFORMANCE