dynamic_pager.8   [plain text]

.\" Copyright (c) 2003 Apple Computer, Inc.  All rights reserved.
.Dd July 8, 2003
.Dt dynamic_pager 8
.Os "Mac OS X"
.Nm dynamic_pager
.Nd external storage manager for dynamic pager
.Nm dynamic_pager
.Op Fl F Ar filename
.Op Fl S Ar filesize
.Op Fl H Ar high-water-trigger
.Op Fl L Ar low-water-trigger
.Op Fl P Ar priority
.Nm dynamic_pager
daemon manages a pool of external swap files
which the kernel uses to support demand paging.
This pool is expanded with new swap files
as load on the system increases.
It is contracted when the swapping resources are no longer needed.  The
.Nm dynamic_pager
daemon also provides a notification service
for those applications which wish to receive notices
when the external paging pool expands or contracts.
.Bl -tag -width Ds
.\" ==========
.It Fl F
The base name of the
.Ar filename
to use for the external paging files.  By default this is
.Pa /private/var/vm/swapfile .
.\" ==========
.It Fl H
If there are less than
.Ar high-water-trigger
bytes free in the external paging files, the kernel will signal
.Nm dynamic_pager
to add a new external paging file.
.\" ==========
.It Fl L
If there are more than
.Ar low-water-trigger
bytes free in the external paging files, the kernel will coalese in-use pages
and signal
.Nm dynamic_pager
to discard an external paging file.
.Ar Low-water-trigger
must be greater than
.Ar high-water-trigger
.Ar filesize .
.\" ==========
.It Fl P
This option is currently unimplemented.
.\" ==========
.It Fl S
The fixed
.Ar filesize
[in bytes] to use for the paging files.  By default
.Nm dynamic_pager
uses variable sized paging files, using larger sized files as paging demands
increase.  The
.Fl S ,
.Fl H
.Fl L
options disable that default and cause
.Nm dynamic_pager
to use a series of fixed sized external paging files.
.Bl -tag -width /Library/Preferences/com.apple.virtualMemory.plist -compact
.It Pa /private/var/vm/swapfile*
Default external paging files.
.It Pa /Library/Preferences/com.apple.virtualMemory.plist
Configuration file.
The following keys can be specified in the configuration file.  Please see 
.Xr plist 5
for more information about property list files.
.Bl -ohang
.It Sy UseEncryptedSwap <boolean>
This optional key activates encrypted swap (aka Secure VM), so that all data is encrypted before being written to a swap file.  The default is on for portable computers and off for other computers.