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SubjectRe: [patch 6/6] mempolicy: update NUMA memory policy documentation
David Rientjes wrote:
> Updates Documentation/vm/numa_memory_policy.txt and
> Documentation/filesystems/tmpfs.txt to describe optional mempolicy mode
> flags.
>
> Cc: Christoph Lameter <clameter@sgi.com>
> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
> Cc: Andi Kleen <ak@suse.de>
> Cc: Randy Dunlap <randy.dunlap@oracle.com>
> Signed-off-by: David Rientjes <rientjes@google.com>
> Signed-off-by: Paul Jackson <pj@sgi.com>
> ---
> Documentation/filesystems/tmpfs.txt | 12 +++
> Documentation/vm/numa_memory_policy.txt | 131 +++++++++++++++++++++++-------
> 2 files changed, 112 insertions(+), 31 deletions(-)
>
> diff --git a/Documentation/vm/numa_memory_policy.txt b/Documentation/vm/numa_memory_policy.txt
> --- a/Documentation/vm/numa_memory_policy.txt
> +++ b/Documentation/vm/numa_memory_policy.txt

> @@ -231,6 +234,80 @@ Components of Memory Policies
> the temporary interleaved system default policy works in this
> mode.
>
> + Linux memory policy supports the following optional mode flag:

flags:

> +
> + MPOL_F_STATIC_NODES: This flag specifies that the nodemask passed by
> + the user should not be remapped if the task or VMA's set of allowed
> + nodes changes after the memory policy has been defined.
> +
> + Without this flag, anytime a mempolicy is rebound because of a
> + change in the set of allowed nodes, the node (Preferred) or
> + nodemask (Bind, Interleave) is remapped to the new set of
> + allowed nodes. This may result in nodes being used that were
> + previously undesired.
> +
> + With this flag, if the user specified nodes overlap with the

user-specified

> + nodes allowed by the task's cpuset, then the memory policy is
> + applied to their intersection. If the two sets of nodes do not
> + overlap, the Default policy is used.
> +
> + For example, consider a task that is attached to a cpuset with
> + mems 1-3 that sets an Interleave policy over the same set. If
> + the cpuset's mems change to 3-5, the Interleave will now occur
> + over nodes 3, 4, and 5. With this flag, however, since only node
> + 3 is allowed from the user's nodemask, the "interleave" only
> + occurs over that node. If no nodes from the user's nodemask are
> + now allowed, the Default behavior is used.
> +
> + MPOL_F_STATIC_NODES cannot be used with MPOL_F_RELATIVE_NODES.
> +


--
~Randy


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