migrate_pages(2) - Linux manual page (original) (raw)

migratepages(2) System Calls Manual migratepages(2)

NAME top

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

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 ***_oldnodes,_
                      **const unsigned long ***_newnodes_**);**

DESCRIPTION top

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

   The _oldnodes_ and _newnodes_ 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)](../man2/mbind.2.html), but different
   from [select(2)](../man2/select.2.html)).

   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](../man3/errno.3.html)_ to
   indicate the error.

ERRORS top

   **EFAULT** Part or all of the memory range specified by
          _oldnodes_/_newnodes_ and _maxnode_ points outside your
          accessible address space.

   **EINVAL** The value specified by _maxnode_ exceeds a kernel-imposed
          limit.  Or, _oldnodes_ or _newnodes_ specifies one or more
          node IDs that are greater than the maximum supported node
          ID.  Or, none of the node IDs specified by _newnodes_ 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

   Linux.

HISTORY top

   Linux 2.6.16.

NOTES top

   For information on library support, see [numa(7)](../man7/numa.7.html).

   Use [get_mempolicy(2)](../man2/get%5Fmempolicy.2.html) 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)](../man2/mbind.2.html)) and/or the specified process (see
   [set_mempolicy(2)](../man2/set%5Fmempolicy.2.html)).  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)](../man2/get%5Fmempolicy.2.html), [mbind(2)](../man2/mbind.2.html), [set_mempolicy(2)](../man2/set%5Fmempolicy.2.html), [numa(3)](../man3/numa.3.html),
   **numa_maps**(5), [cpuset(7)](../man7/cpuset.7.html), [numa(7)](../man7/numa.7.html), [migratepages(8)](../man8/migratepages.8.html), [numastat(8)](../man8/numastat.8.html)

   _Documentation/vm/pagemigration.rst_ in the Linux kernel source
   tree

COLOPHON top

   This page is part of the _man-pages_ (Linux kernel and C library
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Linux man-pages 6.10 2024-07-23 migratepages(2)

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