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MIGRATE_PAGES(2) Linux Programmer's Manual MIGRATE_PAGES(2)
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);
Note: There is no glibc wrapper for this system call; see NOTES.
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
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 maxi‐
mum 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 tar‐
get 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
Glibc does not provide a wrapper for this system call. 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.rst in the Linux kernel source tree
Linux 2021-03-22 MIGRATE_PAGES(2)