| NAME | SYNOPSIS | DESCRIPTION | Page states in the status array | RETURN VALUE | ERRORS | VERSIONS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON | The Linux Programming Interface |
MOVE_PAGES(2) Linux Programmer's Manual MOVE_PAGES(2)
move_pages - move individual pages of a process to another node
#include <numaif.h>
long move_pages(int pid, unsigned long count, void **pages,
const int *nodes, int *status, int flags);
Link with -lnuma.
move_pages() moves the specified pages of the process pid to the memory nodes
specified by nodes. The result of the move is reflected in status. The flags
indicate constraints on the pages to be moved.
pid is the ID of the process in which pages are to be moved. To move pages in
another process, the caller must be privileged (CAP_SYS_NICE) or the real or
effective user ID of the calling process must match the real or saved-set user
ID of the target process. If pid is 0, then move_pages() moves pages of the
calling process.
count is the number of pages to move. It defines the size of the three arrays
pages, nodes, and status.
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 pid.
nodes is an array of integers that specify the desired location for each page.
Each element in the array is a node number. nodes can also be NULL, in which
case move_pages() does not move any pages but instead will return the node
where each page currently resides, in the status array. Obtaining the status
of each page may be necessary to determine pages that need to be moved.
status is an array of integers that return the status of each page. The array
only contains valid values if move_pages() did not return an error.
flags specify what types of pages to move. MPOL_MF_MOVE means that only pages
that are in exclusive use by the process are to be moved. MPOL_MF_MOVE_ALL
means that pages shared between multiple processes can also be moved. The
process must be privileged (CAP_SYS_NICE) to use MPOL_MF_MOVE_ALL.
The following values can be returned in each element of the status array.
0..MAX_NUMNODES
Identifies the node on which the page resides.
-EACCES
The page is mapped by multiple processes and can only be moved if
MPOL_MF_MOVE_ALL is specified.
-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.
-EFAULT
This is a zero page or the memory area is not mapped by the process.
-EIO Unable to write back a page. The page has to be written back in order
to move it since the page is dirty and the file system does not provide
a migration function that would allow the move of dirty pages.
-EINVAL
A dirty page cannot be moved. The file system does not provide a
migration function and has no ability to write back pages.
-ENOENT
The page is not present.
-ENOMEM
Unable to allocate memory on target node.
On success move_pages() returns zero. On error, it returns -1, and sets errno
to indicate the error.
E2BIG Too many pages to move.
EACCES One of the target nodes is not allowed by the current cpuset.
EFAULT Parameter array could not be accessed.
EINVAL Flags other than MPOL_MF_MOVE and MPOL_MF_MOVE_ALL was specified or an
attempt was made to migrate pages of a kernel thread.
ENODEV One of the target nodes is not online.
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.
EPERM The caller specified MPOL_MF_MOVE_ALL without sufficient privileges
(CAP_SYS_NICE). Or, the caller attempted to move pages of a process
belonging to another user but did not have privilege to do so
(CAP_SYS_NICE).
ESRCH Process does not exist.
move_pages() first appeared on Linux in version 2.6.18.
This system call is Linux-specific.
For information on library support, see numa(7).
Use get_mempolicy(2) with the MPOL_F_MEMS_ALLOWED flag to obtain the set of
nodes that are allowed by the current cpuset. Note that this information is
subject to change at any time by manual or automatic reconfiguration of the
cpuset.
Use of this function may result in pages whose location (node) violates the
memory policy established for the specified addresses (See mbind(2)) and/or
the specified process (See set_mempolicy(2)). That is, memory policy does not
constrain the destination nodes used by move_pages().
The <numaif.h> header is not included with glibc, but requires installing
libnuma-devel or a similar package.
get_mempolicy(2), mbind(2), set_mempolicy(2), numa(3), numa_maps(5),
cpuset(7), numa(7), migratepages(8), numa_stat(8)
This page is part of release 3.32 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
Linux 2010-06-11 MOVE_PAGES(2)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface