PSTAT Interfaces

4.21 pstat_getstable().................................................................................................................. 24

4.22 pstat_getstatic()................................................................................................................... 24

4.23 pstat_getstream() ................................................................................................................ 25

4.24 pstat_getswap() ................................................................................................................... 26

4.25 pstat_getvminfo()................................................................................................................ 26

5. Binary Compatibility................................................................................................................ 27

6. Appendix................................................................................................................................... 28

1. Introduction

1.1 Abstract

Pstat is a supported Application Programming Interface (API) that provides many HP-UX

system contexts. It provides a number of wrappers (pstat_get*) and corresponding structures

(struct pst_*) to get information from the kernel. These interfaces are designed in such a way to

allow future expansion of the interface, while preserving source and binary compatibility for

programs written using the pstat interfaces. Pstat interfaces are available in both 64-bit and 32-bit

versions.

Today, many applications read kernel data structures through unsupported interfaces,

such as the /dev/kmem pseudo driver, to get information about open files, resource usage,

process activity etc. Because kernel data structures change from release to release, this access

method is fragile, incurring a high maintenance cost. Replacing such access methods with calls

to the pstat() system call will insulate these applications from the release-to-release variability in

private kernel data structures and eliminate the need to re-release these applications with each

new HP-UX release.

1.2 Purpose of Document

The purpose of this document is to communicate the availability of pstat interfaces and to

give developers guidance on how to take advantage of these supported interfaces. It provides

code examples to demonstrate the calling conventions.

1.3 Intended Audience

This document is intended for HP-UX software developers, system administrators, and end

users, both internal and external to Hewlett-Packard.

1.4 Structure of Document

The document is structured as follows. Section 2 provides an overview of pstat. Section 3

provides a summary of the system contexts available through pstat. Each of the pstat wrappers is

described in detail in Section 4. Code examples that demonstrate the usage of pstat wrappers are

also included. Section 5 explains how pstat supports binary compatibility. Each of the available

contexts is explained in detail in Section 6.

1.5 Related Documentation

• Man page for pstat()

• Header files <sys/pstat.h> and <sys/pstat/*.h>