---
name: "vm_page_io"
section: "9"
platform: "linux"
package: "freebsd-manpages"
version: "6.0-5"
release: "Debian 4.0 (Etch)"
platforms: ["linux"]
url: "https://new.carta.tech/vm_page_io"
---

# vm\_page\_io(9)

ready or unready a page for I/O

## NAME

**vm\_page\_io\_start**, **vm\_page\_io\_finish** – ready or unready a page for I/O

## SYNOPSIS

**#include \<sys/param.h\>**

**#include \<vm/vm.h\>**

**#include \<vm/vm\_page.h\>**

*void*\

**vm\_page\_io\_start**(*vm\_page\_t m*);

*void*\

**vm\_page\_io\_finish**(*vm\_page\_t m*);

## DESCRIPTION

The **vm\_page\_io\_start**() function prepares the page for I/O by incrementing its busy flag by one.

The **vm\_page\_io\_finish**() function lowers the busy count on the page by one, if the resulting busy count is zero, a [wakeup(9)](/wakeup/9.md) will be issued if the page has been marked PG\_WANTED. A page is typically marked PG\_WANTED by a thread to register its interest in the page to either complete I/O or becoming available for general use.

## AUTHORS

This manual page was written by Chad David ⟨davidc@acns.ab.ca⟩ and Alfred Perlstein ⟨alfred@FreeBSD.org⟩.