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.\" This manpage is Copyright (C) 2006 Silicon Graphics, Inc.

.\"                               Christoph Lameter

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.TH MOVE_PAGES 2 2006-10-31 "Linux 2.6.18" "Linux Programmer's Manual"

.SH NAME

move_pages \- Move individual pages of a process to another node

.SH SYNOPSIS

.B #include <numaif.h>

.sp

.BI "long move_pages(int " pid ", unsigned long count, void ** " pages ", const int * " nodes ", int * " status ", int " flags );

.SH DESCRIPTION

.BR move_pages ()

moves

.I count

pages to the

.I nodes.

The result of the move is reflected in

.I status.

The

.I flags

indicate constraints on the pages to be moved.

.I pid

is the process id in which pages are to be moved. Sufficient rights

must exist to move pages of another process. This means the moving

process either has root priviledges, has SYS_NICE administrative rights or

the same owner. If pid is 0 then we move pages of the current process.

.I count

is the number of pages to move. It defines the size of the three

arrays

.I pages,

.I nodes

and

.I status.

.I pages

is an array of pointers to the pages that should be moved. These are pointers

that should be aligned to page boundaries. Addresses are specified as seen by

the process specified by

.I pid.

.I nodes

is either an array of integers that specify the desired location for each

page or it is NULL. Each integer is a node number. If NULL is specified then

move_pages will not move any pages but return the node of each page in

the

.I status

array. Having the status of each page may be necessary to determine

pages that need to be moved.

.I status

is an array of integers that return the status of each page. The array

only contains valid values if

.I move_pages

did not return an error code.

.I flags

specify what types of pages to move.

.B MPOL_MF_MOVE

means that only pages that are in exclusive use by the process

are to be moved.

.B MPOL_MF_MOVE_ALL

means that pages shared between multiple processes can also be moved.

The process must have root priviledges or SYS_NICE priviledges.

.SH Page states in the status array

.TP

.B 0..MAX_NUMNODES

Indicates that the location of the page is on this node.

.TP

.B -ENOENT

The page is not present.

.TP

.B -EACCES

The page is mapped by multiple processes and can only be moved

if

.I MPOL_MF_MOVE_ALL

is specified.

.TP

.B -EBUSY

The page is currently busy and cannot be moved. Try again later.

This occurs if a page is undergoing I/O or another kernel subsystem

is holding a reference to the page.

.TP

.B -EFAULT

This is a zero page or the memory area is not mapped by the process.

.TP

.B -ENOMEM

Unable to allocate memory on target node.

.TP

.B -EIO

Unable to write back a page. The page has to be written back

in order to move ti since the page is dirty and the filesystem

has not provide a migration function that would allow the move

of dirty pages.

.TP

.B -EINVAL

A dirty page cannot be moved. The filesystem does not

provide a migration function and has no ability to write back pages.

.SH "RETURN VALUE"

On success

.B move_pages

returns zero.

.SH ERRORS

.TP

.B -ENOENT

No pages were found that require moving. All pages are either already

on the target node, not present, had an invalid address or could not be

moved because they were mapped by multiple processes.

.TP

.B -EINVAL

Flags other than

.I MPOL_MF_MOVE

and

.I MPOL_MF_MOVE_ALL

was specified or an attempt was made to migrate pages of a kernel thread.

.TP

.B -EPERM

.I MPOL_MF_MOVE_ALL

specified without sufficient privileges or an attempt to move a process

belonging to another user.

.TP

.B -EACCESS

On of the target nodes is not allowed by the current cpuset.

.TP

.B -ENODEV

On of the target nodes is not online.

.TP

.B -ESRCH

Process does not exist.

.TP

.B -E2BIG

Too many pages to move.

.TP

.B -EFAULT

Parameter array could not be accessed.

.SH "SEE ALSO"

.BR numa_maps (5),

.BR migratepages (8),

.BR numa_stat (8),

.BR numa (3)