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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  integers  (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 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
       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 3.65 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/.



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