perfstat_process_util Subroutine

Purpose

Calculates process utilization metrics.

Library

perfstat library (libperfstat.a)

Syntax

#include <libperfstat.h>

int perfstat_process (data, userbuff, sizeof_userbuff, desired_number)
perfstat_id_t * data;
perfstat_process_t * userbuff;
int  sizeof_userbuff ;
int  desired_number ;

Description

The perfstat_process_util subroutine provides the interface for process utilization metrics. The perfstat_process subroutine retrieves one or more process statistics to populate the perfstat_process_t data structure. The perfstat_process_util subroutine uses the current and previous values to calculate the utilization-related metrics. If the name and userbuff parameters are set to NULL, and the sizeof_userbuff parameter is set to 0, then the size of the current version of the perfstat_process_t data structure is returned. If the desired_number parameter is set to 0, the number of current elements, from the perfstat_rawdata_t data structure, is returned.

Parameters

Table 1. Parameters
Item	Description
`data`	Specifies that the `data` parameter is of the type `perfstat_rawdata_t`. The `perfstat_rawdata_t` data structure can take the current and the previous values to calculate the utilization-related metrics.
`userbuff`	Specifies the memory area to be filled with one or more `perfstat_process_t` data structures.
`sizeof_userbuff`	Specifies the size of the `perfstat_process_t` data structure. Note: To obtain the size of the latest version of the data structure `perfstat_process_t`, set the parameter `sizeof_userbuff` to 0, and the parameters `name` and `userbuff` to NULL.
`desired_number`	Specifies the number of the `perfstat_process_t` structures to copy to the `userbuff` parameter.

Return Values

Unless the perfstat_process_util subroutine is used to retrieve the number of available structures, the number of structures that are filled is returned upon successful completion. If unsuccessful, a value of -1 is returned and the errno global variable is set.

Error Codes

The perfstat_process_util subroutine is unsuccessful if the following error code is true:

Table 2. Error Codes
Item	Description
`EINVAL`	One of the parameters is not valid.

Files

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