Add a movablecore= parameter for sizing ZONE_MOVABLE

This patch adds a new parameter for sizing ZONE_MOVABLE called
movablecore=.  While kernelcore= is used to specify the minimum amount of
memory that must be available for all allocation types, movablecore= is
used to specify the minimum amount of memory that is used for migratable
allocations.  The amount of memory used for migratable allocations
determines how large the huge page pool could be dynamically resized to at
runtime for example.

How movablecore is actually handled is that the total number of pages in
the system is calculated and a value is set for kernelcore that is

kernelcore == totalpages - movablecore

Both kernelcore= and movablecore= can be safely specified at the same time.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1794affbd06..9a541486fb7 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -833,6 +833,16 @@ and is between 256 and 4096 characters. It is defined in the file
                         use the HighMem zone if it exists, and the Normal
                         zone if it does not.
 
+        movablecore=nn[KMG]     [KNL,IA-32,IA-64,PPC,X86-64] This parameter
+                        is similar to kernelcore except it specifies the
+                        amount of memory used for migratable allocations.
+                        If both kernelcore and movablecore is specified,
+                        then kernelcore will be at *least* the specified
+                        value but may be more. If movablecore on its own
+                        is specified, the administrator must be careful
+                        that the amount of memory usable for all allocations
+                        is not too small.
+
         keepinitrd      [HW,ARM]
 
         kstack=N        [IA-32,X86-64] Print N words from the kernel stack