Hi Michael,

On Wed, Oct 12, 2016 at 09:55:16AM +0200, Michael Kerrisk (man-pages) wrote:

Hello Piotr,

On 10/10/2016 06:23 PM, Piotr Kwapulinski wrote:

quoted

The MPOL_LOCAL mode has been implemented by
Peter Zijlstra [off-list ref]
(commit: 479e2802d09f1e18a97262c4c6f8f17ae5884bd8).
Add the documentation for this mode.

Thanks. I've applied this patch. I have a question below.

quoted

Signed-off-by: Piotr Kwapulinski <redacted>
---
This version fixes grammar
---
 man2/mbind.2         | 28 ++++++++++++++++++++++++----
 man2/set_mempolicy.2 | 19 ++++++++++++++++++-
 2 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/man2/mbind.2 b/man2/mbind.2
index 3ea24f6..854580c 100644
--- a/man2/mbind.2
+++ b/man2/mbind.2

@@ -130,8 +130,9 @@ argument must specify one of
 .BR MPOL_DEFAULT ,
 .BR MPOL_BIND ,
 .BR MPOL_INTERLEAVE ,
+.BR MPOL_PREFERRED ,
 or
-.BR MPOL_PREFERRED .
+.BR MPOL_LOCAL .
 All policy modes except
 .B MPOL_DEFAULT
 require the caller to specify via the

@@ -258,9 +259,26 @@ and
 .I maxnode
 arguments specify the empty set, then the memory is allocated on
 the node of the CPU that triggered the allocation.
-This is the only way to specify "local allocation" for a
-range of memory via
-.BR mbind ().
+
+.B MPOL_LOCAL
+specifies the "local allocation", the memory is allocated on
+the node of the CPU that triggered the allocation, "local node".
+The
+.I nodemask
+and
+.I maxnode
+arguments must specify the empty set. If the "local node" is low
+on free memory the kernel will try to allocate memory from other
+nodes. The kernel will allocate memory from the "local node"
+whenever memory for this node is available. If the "local node"
+is not allowed by the process's current cpuset context the kernel
+will try to allocate memory from other nodes. The kernel will
+allocate memory from the "local node" whenever it becomes allowed
+by the process's current cpuset context. In contrast
+.B MPOL_DEFAULT
+reverts to the policy of the process which may have been set with
+.BR set_mempolicy (2).
+It may not be the "local allocation".

What is the sense of "may not be" here? (And repeated below).
Is the meaning "this could be something other than"?
Presumably the answer is yes, in which case I'll clarify
the wording there. Let me know.

Cheers,

Michael

That's right. This could be "local allocation" or any other memory policy.

Thanks
Piotr Kwapulinski

quoted

 
 If
 .B MPOL_MF_STRICT

@@ -440,6 +458,8 @@ To select explicit "local allocation" for a memory range,
 specify a
 .I mode
 of
+.B MPOL_LOCAL
+or
 .B MPOL_PREFERRED
 with an empty set of nodes.
 This method will work for

diff --git a/man2/set_mempolicy.2 b/man2/set_mempolicy.2
index 1f02037..22b0f7c 100644
--- a/man2/set_mempolicy.2
+++ b/man2/set_mempolicy.2

@@ -79,8 +79,9 @@ argument must specify one of
 .BR MPOL_DEFAULT ,
 .BR MPOL_BIND ,
 .BR MPOL_INTERLEAVE ,
+.BR MPOL_PREFERRED ,
 or
-.BR MPOL_PREFERRED .
+.BR MPOL_LOCAL .
 All modes except
 .B MPOL_DEFAULT
 require the caller to specify via the

@@ -211,6 +212,22 @@ arguments specify the empty set, then the policy
 specifies "local allocation"
 (like the system default policy discussed above).
 
+.B MPOL_LOCAL
+specifies the "local allocation", the memory is allocated on
+the node of the CPU that triggered the allocation, "local node".
+The
+.I nodemask
+and
+.I maxnode
+arguments must specify the empty set. If the "local node" is low
+on free memory the kernel will try to allocate memory from other
+nodes. The kernel will allocate memory from the "local node"
+whenever memory for this node is available. If the "local node"
+is not allowed by the process's current cpuset context the kernel
+will try to allocate memory from other nodes. The kernel will
+allocate memory from the "local node" whenever it becomes allowed
+by the process's current cpuset context.
+
 The thread memory policy is preserved across an
 .BR execve (2),
 and is inherited by child threads created using

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/

--
Piotr Kwapulinski