ulCommand (ULONG) - input

Command

DosPerfSysCall accepts the following command:

CMD_KI_RDCNT (0x63)

Read CPU utilization information in both uniprocessor and symmetric multi-processor (SMP) environments by taking a snapshot of the time stamp counters. To determine CPU utilization, the application must compute the difference between two time stamp snapshots using 64-bit arithmetic. See the example code for details.

ulParm1 (ULONG) - in/out

Command specific parameter 1

Parameter usage depends on the command specified:

CMD_KI_RDCNT

Pointer to an array of CPUUTIL structures, with one entry for each processor. On a 4-way SMP machine, the array definition would be:

  CPUUTIL CPUUtil[4];   /* For processor IDs 0, 1, 2, and 3 */

since processor numbers and arrays are both 0-based. ulParm1 would be set to the address of CPUUtil[0].

ulParm2 and ulParm3 are not used and should be set to zero.

ulParm2 (ULONG) - in/out

Command specific parameter 2

Parameter usage depends on the command specified:

CMD_KI_RDCNT

0 (reserved)

ulParm3 (ULONG) - in/out

Command specific parameter 3

Parameter usage depends on the command specified:

CMD_KI_RDCNT

0 (reserved)

ulrc (APIRET) - returns

Return Code.

DosPerfSysCall returns one of the following values:

• NO_ERROR 1
  ERROR_INVALID_FUNCTION
  For a full list of error codes, see Errors.

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