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authorDavid Rientjes <rientjes@google.com>2008-04-28 02:12:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-28 08:58:19 -0700
commit4c50bc0116cf3cc35e7152d6a8424b4db65f52d6 (patch)
tree99c617602cc1946fc86b48e9a35f14f9f354cf67 /mm/shmem.c
parent7ea931c9fc80c4d0a4306c30ec92eb0f1d922a0b (diff)
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mempolicy: add MPOL_F_RELATIVE_NODES flag
Adds another optional mode flag, MPOL_F_RELATIVE_NODES, that specifies nodemasks passed via set_mempolicy() or mbind() should be considered relative to the current task's mems_allowed. When the mempolicy is created, the passed nodemask is folded and mapped onto the current task's mems_allowed. For example, consider a task using set_mempolicy() to pass MPOL_INTERLEAVE | MPOL_F_RELATIVE_NODES with a nodemask of 1-3. If current's mems_allowed is 4-7, the effected nodemask is 5-7 (the second, third, and fourth node of mems_allowed). If the same task is attached to a cpuset, the mempolicy nodemask is rebound each time the mems are changed. Some possible rebinds and results are: mems result 1-3 1-3 1-7 2-4 1,5-6 1,5-6 1,5-7 5-7 Likewise, the zonelist built for MPOL_BIND acts on the set of zones assigned to the resultant nodemask from the relative remap. In the MPOL_PREFERRED case, the preferred node is remapped from the currently effected nodemask to the relative nodemask. This mempolicy mode flag was conceived of by Paul Jackson <pj@sgi.com>. 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> 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 'mm/shmem.c')
-rw-r--r--mm/shmem.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 3e9fda0ca470..9435f298dd75 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1128,6 +1128,12 @@ static int shmem_parse_mpol(char *value, unsigned short *policy,
if (flags) {
if (!strcmp(flags, "static"))
*mode_flags |= MPOL_F_STATIC_NODES;
+ if (!strcmp(flags, "relative"))
+ *mode_flags |= MPOL_F_RELATIVE_NODES;
+
+ if ((*mode_flags & MPOL_F_STATIC_NODES) &&
+ (*mode_flags & MPOL_F_RELATIVE_NODES))
+ err = 1;
}
out:
/* Restore string for error message */