admin-guide/mm/numa_memory_policy.rst

17 which is an administrative mechanism for restricting the nodes from which
40 	allocations across all nodes with "sufficient" memory, so as
164 an optional set of nodes.  The mode determines the behavior of the
166 and the optional set of nodes can be viewed as the arguments to the
188 	does not use the optional set of nodes.
190 	It is an error for the set of nodes specified for this policy to
195 	nodes specified by the policy.  Memory will be allocated from
202 	allocation fails, the kernel will search other nodes, in order
222 	page granularity, across the nodes specified in the policy.
227 	Interleave mode indexes the set of nodes specified by the
230 	nodes specified by the policy.  It then attempts to allocate a
237 	the set of nodes specified by the policy using a node counter
240 	This will tend to spread the pages out over the nodes
249 	a memory pressure on all nodes in the nodemask, the allocation
250 	can fall back to all existing numa nodes. This is effectively
258 	Weighted interleave allocates pages on nodes according to a
259 	weight.  For example if nodes [0,1] are weighted [5,2], 5 pages
267 	nodes changes after the memory policy has been defined.
270         change in the set of allowed nodes, the preferred nodemask (Preferred
272         remapped to the new set of allowed nodes.  This may result in nodes
275 	With this flag, if the user-specified nodes overlap with the
276 	nodes allowed by the task's cpuset, then the memory policy is
277 	applied to their intersection.  If the two sets of nodes do not
283 	over nodes 3, 4, and 5.  With this flag, however, since only node
285 	occurs over that node.  If no nodes from the user's nodemask are
296 	set of allowed nodes.  The kernel stores the user-passed nodemask,
297 	and if the allowed nodes changes, then that original nodemask will
298 	be remapped relative to the new set of allowed nodes.
302 	nodes, the node (Preferred) or nodemask (Bind, Interleave) is
303 	remapped to the new set of allowed nodes.  That remap may not
305 	set of allowed nodes upon successive rebinds: a nodemask of
307 	allowed nodes is restored to its original state.
311 	nodes.  In other words, if nodes 0, 2, and 4 are set in the user's
313 	Bind or Interleave case, the third and fifth) nodes in the set of
314 	allowed nodes.  The nodemask passed by the user represents nodes
315 	relative to task or VMA's set of allowed nodes.
317 	If the user's nodemask includes nodes that are outside the range
318 	of the new set of allowed nodes (for example, node 5 is set in
319 	the user's nodemask when the set of allowed nodes is only 0-3),
326 	interleave now occurs over nodes 3,5-7.  If the cpuset's mems
327 	then change to 0,2-3,5, then the interleave occurs over nodes
334 	memory nodes 0 to N-1, where N is the number of memory nodes the
336 	set of memory nodes allowed by the task's cpuset, as that may
361 and NUMA nodes.  "Usage" here means one of the following:
371    BIND policy nodemask is used, by reference, to filter ineligible nodes.
408    on different NUMA nodes.  This extra overhead can be avoided by always
435 specified by the 'mode' argument and the set of nodes defined by
506 that require a node or set of nodes, the nodes are restricted to the set of
507 nodes whose memories are allowed by the cpuset constraints.  If the nodemask
508 specified for the policy contains nodes that are not allowed by the cpuset and
509 MPOL_F_RELATIVE_NODES is not used, the intersection of the set of nodes
510 specified for the policy and the set of nodes with memory is used.  If the
512 installed.  If MPOL_F_RELATIVE_NODES is used, the policy's nodes are mapped
513 onto and folded into the task's set of allowed nodes as previously described.
518 any of the tasks install shared policy on the region, only nodes whose