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authorDavid Rientjes <rientjes@google.com>2008-04-28 02:12:34 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-28 08:58:20 -0700
commit3e1f064562fcff7bf3856bc1d00dfa84d4f121cc (patch)
tree9ebc17449238ab5284b72f634405044376dc816b /Documentation/vm
parent3842b46de626d1a3c44ad280d67ab0a4dc047d13 (diff)
mempolicy: disallow static or relative flags for local preferred mode
MPOL_F_STATIC_NODES and MPOL_F_RELATIVE_NODES don't mean anything for MPOL_PREFERRED policies that were created with an empty nodemask (for purely local allocations). They'll never be invalidated because the allowed mems of a task changes or need to be rebound relative to a cpuset's placement. Also fixes a bug identified by Lee Schermerhorn that disallowed empty nodemasks to be passed to MPOL_PREFERRED to specify local allocations. [A different, somewhat incomplete, patch already existed in 25-rc5-mm1.] Cc: Paul Jackson <pj@sgi.com> 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: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/vm')
-rw-r--r--Documentation/vm/numa_memory_policy.txt16
1 files changed, 14 insertions, 2 deletions
diff --git a/Documentation/vm/numa_memory_policy.txt b/Documentation/vm/numa_memory_policy.txt
index 706410dfb9e..1c7dd21623d 100644
--- a/Documentation/vm/numa_memory_policy.txt
+++ b/Documentation/vm/numa_memory_policy.txt
@@ -205,6 +205,12 @@ Components of Memory Policies
local allocation for a specific range of addresses--i.e. for
VMA policies.
+ It is possible for the user to specify that local allocation is
+ always preferred by passing an empty nodemask with this mode.
+ If an empty nodemask is passed, the policy cannot use the
+ MPOL_F_STATIC_NODES or MPOL_F_RELATIVE_NODES flags described
+ below.
+
MPOL_INTERLEAVED: This mode specifies that page allocations be
interleaved, on a page granularity, across the nodes specified in
the policy. This mode also behaves slightly differently, based on
@@ -254,7 +260,10 @@ Components of Memory Policies
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.
+ MPOL_F_STATIC_NODES cannot be combined with the
+ MPOL_F_RELATIVE_NODES flag. It also cannot be used for
+ MPOL_PREFERRED policies that were created with an empty nodemask
+ (local allocation).
MPOL_F_RELATIVE_NODES: This flag specifies that the nodemask passed
by the user will be mapped relative to the set of the task or VMA's
@@ -301,7 +310,10 @@ Components of Memory Policies
set of memory nodes allowed by the task's cpuset, as that may
change over time.
- MPOL_F_RELATIVE_NODES cannot be used with MPOL_F_STATIC_NODES.
+ MPOL_F_RELATIVE_NODES cannot be combined with the
+ MPOL_F_STATIC_NODES flag. It also cannot be used for
+ MPOL_PREFERRED policies that were created with an empty nodemask
+ (local allocation).
MEMORY POLICY APIs