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3 .\" This manpage is Copyright (C) 2006 Silicon Graphics, Inc.
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15 .\" FIXME Should programs normally be using this API directly, or should
16 .\" they rather be using interfaces in the numactl package?
17 .\" (e.g., compare with recommendation in mbind(2)).
18 .TH MOVE_PAGES 2 2008-10-06 "Linux" "Linux Programmer's Manual"
20 move_pages \- move individual pages of a process to another node
23 .B #include <numaif.h>
25 .BI "long move_pages(int " pid ", unsigned long count, void **" pages ,
26 .BI " const int *" nodes ", int *" status ", int " flags );
34 to the memory nodes specified by
36 The result of the move is reflected in
40 indicate constraints on the pages to be moved.
43 is the ID of the process in which pages are to be moved.
44 To move pages in another process,
45 the caller must be privileged
47 or the real or effective user ID of the calling process must match the
48 real or saved-set user ID of the target process.
53 moves pages of the calling process.
56 is the number of pages to move.
57 It defines the size of the three arrays
64 is an array of pointers to the pages that should be moved.
65 These are pointers that should be aligned to page boundaries.
66 .\" FIXME what if they are not aligned?
67 Addresses are specified as seen by the process specified by
71 is an array of integers that specify the desired location for each page.
72 Each element in the array is a node number.
74 can also be NULL, in which case
76 does not move any pages but instead will return the node
77 where each page currently resides, in the
80 Obtaining the status of each page may be necessary to determine
81 pages that need to be moved.
84 is an array of integers that return the status of each page.
85 The array only contains valid values if
87 did not return an error.
90 specify what types of pages to move.
92 means that only pages that are in exclusive use by the process
95 means that pages shared between multiple processes can also be moved.
96 The process must be privileged
99 .BR MPOL_MF_MOVE_ALL .
100 .SH Page states in the status array
101 The following values can be returned in each element of the
106 Identifies the node on which the page resides.
109 The page is mapped by multiple processes and can only be moved if
114 The page is currently busy and cannot be moved.
116 This occurs if a page is undergoing I/O or another kernel subsystem
117 is holding a reference to the page.
120 This is a zero page or the memory area is not mapped by the process.
123 Unable to write back a page.
124 The page has to be written back
125 in order to move it since the page is dirty and the file system
126 does not provide a migration function that would allow the move
130 A dirty page cannot be moved.
131 The file system does not
132 provide a migration function and has no ability to write back pages.
135 The page is not present.
138 Unable to allocate memory on target node.
143 .\" FIXME Is the following quite true: does the wrapper in numactl
144 .\" do the right thing?
145 On error, it returns \-1, and sets
147 to indicate the error.
151 Too many pages to move.
154 .\" FIXME Clarify "current cpuset". Is that the cpuset of the caller
156 One of the target nodes is not allowed by the current cpuset.
159 Parameter array could not be accessed.
166 was specified or an attempt was made to migrate pages of a kernel thread.
169 One of the target nodes is not online.
172 No pages were found that require moving.
173 All pages are either already
174 on the target node, not present, had an invalid address or could not be
175 moved because they were mapped by multiple processes.
180 without sufficient privileges
181 .RB ( CAP_SYS_NICE ).
182 Or, the caller attempted to move pages of a process belonging
183 to another user but did not have privilege to do so
184 .RB ( CAP_SYS_NICE ).
187 Process does not exist.
190 first appeared on Linux in version 2.6.18.
192 This system call is Linux-specific.
194 For information on library support, see
198 .BR get_mempolicy (2)
200 .B MPOL_F_MEMS_ALLOWED
201 flag to obtain the set of nodes that are allowed by
202 .\" FIXME Clarify "current cpuset". Is that the cpuset of the caller
205 Note that this information is subject to change at any
206 time by manual or automatic reconfiguration of the cpuset.
208 Use of this function may result in pages whose location
209 (node) violates the memory policy established for the
210 specified addresses (See
212 and/or the specified process [See
213 .BR set_mempolicy (2)).
214 That is, memory policy does not constrain the destination
218 .BR get_mempolicy (2),
220 .BR set_mempolicy (2),
225 .BR migratepages (8),