migrate_pages(2) — Linux manual page


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

NAME         top

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

SYNOPSIS         top

       #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         top

       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         top

       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         top

       EFAULT Part or all of the memory range specified by
              old_nodes/new_nodes and maxnode points outside your accessible
              address space.

       EINVAL The value specified by maxnode exceeds a kernel-imposed limit.
              Or, old_nodes or new_nodes specifies one or more node IDs that
              are greater than the maximum supported node ID.  Or, none of
              the node IDs specified by new_nodes are on-line and allowed by
              the process's current cpuset context, or none of the specified
              nodes contain memory.

       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         top

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

CONFORMING TO         top

       This system call is Linux-specific.

NOTES         top

       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         top

       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.rst in the Linux kernel source tree

COLOPHON         top

       This page is part of release 5.08 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

Linux                            2019-03-06                 MIGRATE_PAGES(2)

Pages that refer to this page: swapoff(2)swapon(2)syscalls(2)numa(3)capabilities(7)numa(7)