[PATCH] x86-64: configurable fake numa node sizes

Extends the numa=fake x86_64 command-line option to allow for configurable
node sizes.  These nodes can be used in conjunction with cpusets for coarse
memory resource management.

The old command-line option is still supported:
  numa=fake=32	gives 32 fake NUMA nodes, ignoring the NUMA setup of the
		actual machine.

But now you may configure your system for the node sizes of your choice:
  numa=fake=2*512,1024,2*256
		gives two 512M nodes, one 1024M node, two 256M nodes, and
		the rest of system memory to a sixth node.

The existing hash function is maintained to support the various node sizes
that are possible with this implementation.

Each node of the same size receives roughly the same amount of available
pages, regardless of any reserved memory with its address range.  The total
available pages on the system is calculated and divided by the number of equal
nodes to allocate.  These nodes are then dynamically allocated and their
borders extended until such time as their number of available pages reaches
the required size.

Configurable node sizes are recommended when used in conjunction with cpusets
for memory control because it eliminates the overhead associated with scanning
the zonelists of many smaller full nodes on page_alloc().

Cc: Andi Kleen <ak@suse.de>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Paul Jackson <pj@sgi.com>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt
index 85f51e5a749f..7500aad95f3c 100644
--- a/Documentation/x86_64/boot-options.txt
+++ b/Documentation/x86_64/boot-options.txt
@@ -149,7 +149,13 @@ NUMA
 
   numa=noacpi   Don't parse the SRAT table for NUMA setup
 
-  numa=fake=X   Fake X nodes and ignore NUMA setup of the actual machine.
+  numa=fake=CMDLINE
+                If a number, fakes CMDLINE nodes and ignores NUMA setup of the
+                actual machine.  Otherwise, system memory is configured
+                depending on the sizes and coefficients listed.  For example:
+                        numa=fake=2*512,1024,4*256
+                gives two 512M nodes, a 1024M node, and four 256M nodes.  The
+                remaining system RAM is allocated to an additional node.
 
   numa=hotadd=percent
                 Only allow hotadd memory to preallocate page structures upto