migrate_pages(2) System Calls Manual migrate_pages(2)
NAME
migrate_pages - move all pages in a process to another set of nodes
LIBRARY
NUMA (Non-Uniform Memory Access) policy library (libnuma, -lnuma)
SYNOPSIS
#include <numaif.h>
long migrate_pages(int pid, unsigned long maxnode,
const unsigned long *old_nodes,
const unsigned long *new_nodes);
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 pos-
sible, 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 main-
tained 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
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
The migrate_pages() system call first appeared in Linux 2.6.16.
STANDARDS
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 au-
tomatic reconfiguration of the cpuset.
Use of migrate_pages() may result in pages whose location (node) vio-
lates 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 mi-
grate_pages().
The <numaif.h> header is not included with glibc, but requires in-
stalling 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.rst in the Linux kernel source tree
Linux man-pages 6.03 2022-12-04 migrate_pages(2)
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