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"
.Sh NAME
.Nm dynamic_pager
.Nd dynamic pager external storage manager
.Sh SYNOPSIS
.Nm dynamic_pager
.Op Fl E
.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
.Sh DESCRIPTION
The
.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, and 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.
.Sh OPTIONS
.Bl -tag -width Ds
.It Fl E
Encrypt the data in the swap files.
.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 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
and
.Fl L
options disable that default and cause
.Nm dynamic_pager
to use a series of fixed sized external paging files.
.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.
.El
.Sh FILES
.Bl -tag -width /private/var/vp/swapfile* -compact
.It Pa /private/var/vm/swapfile*
Default external paging files.
.El