migrate_pages(2) — Linux manual page


migrate_pages(2)           System Calls Manual          migrate_pages(2)

NAME         top

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

LIBRARY         top

       NUMA (Non-Uniform Memory Access) policy library (libnuma, -lnuma)

SYNOPSIS         top

       #include <numaif.h>

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

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.

STANDARDS         top


HISTORY         top

       Linux 2.6.16.

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

COLOPHON         top

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Linux man-pages 6.9.1          2024-05-02               migrate_pages(2)

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