migrate_pages - move all pages in a process to another set of nodes
#include <numaif.h>
long migrate_pages(int pid, unsigned long maxnode,
const unsigned long *old_nodes,
const unsigned long *new_nodes);
Link with -lnuma
.
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.
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.
Part or all of the memory range specified by old_nodes
/new_nodes
and maxnode
points outside your accessible address space.
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.
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.
No process matching pid
could be found.
The migrate_pages() system call first appeared on Linux in version 2.6.16.
This system call is Linux-specific.
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.
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
This page is part of release 5.10 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 https://www.kernel.org/doc/man-pages/.