[PATCH] mm: add noaliencache boot option to disable numa alien caches

When using numa=fake on non-NUMA hardware there is no benefit to having the
alien caches, and they consume much memory.

Add a kernel boot option to disable them.

Christoph sayeth "This is good to have even on large NUMA.  The problem is
that the alien caches grow by the square of the size of the system in terms of
nodes."

Cc: Christoph Lameter <clameter@engr.sgi.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 2e1898e4e8f..2ddc43ef4de 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1012,6 +1012,10 @@ and is between 256 and 4096 characters. It is defined in the file
                         emulation library even if a 387 maths coprocessor
                         is present.
 
+        noaliencache    [MM, NUMA] Disables the allcoation of alien caches in
+                        the slab allocator.  Saves per-node memory, but will
+                        impact performance on real NUMA hardware.
+
         noalign         [KNL,ARM]
 
         noapic          [SMP,APIC] Tells the kernel to not make use of any