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| author | David Rientjes <rientjes@google.com> | 2008-04-28 02:12:34 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-28 08:58:20 -0700 |
| commit | 3e1f064562fcff7bf3856bc1d00dfa84d4f121cc (patch) | |
| tree | 9ebc17449238ab5284b72f634405044376dc816b /Documentation/vm/numa_memory_policy.txt | |
| parent | 3842b46de626d1a3c44ad280d67ab0a4dc047d13 (diff) | |
| download | lwn-3e1f064562fcff7bf3856bc1d00dfa84d4f121cc.tar.gz lwn-3e1f064562fcff7bf3856bc1d00dfa84d4f121cc.zip | |
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/numa_memory_policy.txt')
| -rw-r--r-- | Documentation/vm/numa_memory_policy.txt | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/Documentation/vm/numa_memory_policy.txt b/Documentation/vm/numa_memory_policy.txt index 706410dfb9e5..1c7dd21623d2 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 |