[ Bottom of Page | Previous Page | Next Page | Contents | Index | Library Home | Legal | Search ]

Technical Reference: Kernel and Subsystems, Volume 1

vms_iowait Kernel Service

Purpose

Waits for the completion of all page-out operations for pages in the virtual memory object.

Syntax

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/vmuser.h>


int vms_iowait ( vmid)
vmid_t vmid;

Parameter

vmid Identifies the virtual memory object for which to wait.

Description

The vms_iowait kernel service performs two tasks. First, it determines the I/O level at which all currently scheduled page-outs are complete for the virtual memory object specified by the vmid parameter. Then, the vms_iowait service places the current process in a wait state until this I/O level has been reached.

The I/O level value is a count of page-out operations kept for each virtual memory object.

The I/O level accounts for out-of-order processing by not incrementing the I/O level for new page-out requests until all previous requests are complete. Because of this, processes waiting on different I/O levels can be awakened after a single page-out operation completes.

If the caller holds the kernel lock, the vms_ iowait service releases the kernel lock before waiting and reacquires it afterwards.

Execution Environment

The vms_iowait kernel service can be called from the process environment only.

Return Values

0 Indicates that the page-out operations completed.
EIO Indicates that an error occurred while performing I/O.

Related Information

Memory Kernel Services and Understanding Virtual Memory Manager Interfaces in AIX 5L Version 5.2 Kernel Extensions and Device Support Programming Concepts.

[ Top of Page | Previous Page | Next Page | Contents | Index | Library Home | Legal | Search ]