MIGRATE_PAGES(2)                    Linux Programmer's Manual                    MIGRATE_PAGES(2)



NAME
       migrate_pages - move all pages in a process to another set of nodes

SYNOPSIS
       #include <numaif.h>

       long migrate_pages(int pid, unsigned long maxnode,
                          const unsigned long *old_nodes,
                          const unsigned long *new_nodes);

       Link with -lnuma.

DESCRIPTION
       migrate_pages()  attempts  to  move  all pages of the process pid that are in memory nodes
       old_nodes to the memory nodes in new_nodes.  Pages not located in any  node  in  old_nodes
       will  not  be  migrated.   As  far as possible, the kernel maintains the relative topology
       relationship inside old_nodes during the migration to new_nodes.

       The old_nodes and new_nodes arguments are pointers to bit masks of node numbers,  with  up
       to maxnode bits in each mask.  These masks are maintained as arrays of unsigned long inte‐
       gers (in the last long integer, the bits beyond those specified by maxnode  are  ignored).
       The maxnode argument is the maximum node number in the bit mask plus one (this is the same
       as in mbind(2), but different from select(2)).

       The pid argument is the ID of the process whose 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 migrate_pages() moves pages of the calling process.

       Pages  shared  with  another  process will be moved only if the initiating process has the
       CAP_SYS_NICE privilege.

RETURN VALUE
       On success migrate_pages() returns the number of pages that could not be  moved  (i.e.,  a
       return  of  zero  means that all pages were successfully moved).  On error, it returns -1,
       and sets errno to indicate the error.

ERRORS
       EPERM  Insufficient privilege (CAP_SYS_NICE) to move pages of  the  process  specified  by
              pid, or insufficient privilege (CAP_SYS_NICE) to access the specified target nodes.

       ESRCH  No process matching pid could be found.

VERSIONS
       The migrate_pages() system call first appeared on Linux in version 2.6.16.

CONFORMING TO
       This system call is Linux-specific.

NOTES
       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 calling process's cpuset.  Note that this information is subject to  change
       at any time by manual or automatic reconfiguration of the cpuset.

       Use  of migrate_pages() may result in pages whose location (node) violates the memory pol‐
       icy 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 migrate_pages().

       The <numaif.h> header is not included with glibc, but requires installing libnuma-devel or
       a similar package.

SEE ALSO
       get_mempolicy(2),  mbind(2),  set_mempolicy(2), numa(3), numa_maps(5), cpuset(7), numa(7),
       migratepages(8), numastat(8)

       Documentation/vm/page_migration in the Linux kernel source tree

COLOPHON
       This page is part of release 3.74 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at http://www.kernel.org/doc/man-pages/.



Linux                                       2012-08-01                           MIGRATE_PAGES(2)