perfstat_cpu_total Subroutine

Purpose

Retrieves global processor usage statistics.

Library

Perfstat library (libperfstat.a)

Syntax

#include <libperfstat.h>

int perfstat_cpu_total (name, userbuff, sizeof_struct, desired_number)
perfstat_id_t *name;
perfstat_cpu_total_t *userbuff;
size_t sizeof_struct;
int desired_number;

Description

The perfstat_cpu_total subroutine returns global processor usage statistics in a perfstat_cpu_total_t structure.

To get statistics that are global to the whole system, the name parameter must be set to NULL, the userbuff parameter must be allocated, and the desired_number parameter must be set to 1.

The perfstat_cpu_total subroutine retrieves information from the ODM database. This information is automatically cached into a dictionary which is assumed to be frozen once loaded. The perfstat_reset subroutine must be called to flush the dictionary whenever the machine configuration has changed.

In AIX® 5.3 and later, SPLPAR environments virtualize physical processors. To help accurately measure the resource used in a virtualized environment, the POWER5 family of processors implements a register PURR (Processor Utilization Resource Register) for each core. The PURR is a 64-bit counter with the same units as the timebase register and tracks the real physical processor resource used on a per-thread or per-partition level. The PURR registers are not compatible with previous global counters (user, system, idle and wait fields) returned by the perfstat_cpu and the perfstat_cpu_total subroutines. All data consumers requiring processor use must be modified to support PURR-based computations as shown in the example for the perfstat_partition_total interface under Perfstat API programming.

This subroutine returns only global processor statistics inside a workload partition (WPAR).

Parameters

Item Description
name Must set to NULL.
userbuff Points to the memory area that is to be filled with the perfstat_cpu_total_t structure.
sizeof_struct Specifies the size of the perfstat_cpu_total_t structure: sizeof(perfstat_cpu_total_t).
desired_number Must set to 1.

Return Values

Upon successful completion, the number of structures filled is returned. If unsuccessful, a value of -1 is returned and the errno global variable is set.

Error Codes

The perfstat_cpu_total subroutine is unsuccessful if one of the following is true:

Item Description
EINVAL One of the parameters is not valid.
EFAULT Insufficient memory.
ENOMEM The string default length is too short.

Files

The libperfstat.h file defines standard macros, data types, and subroutines.