SLUB: support slub_debug on by default

[mirror_ubuntu-artful-kernel.git] / Documentation / kernel-parameters.txt

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4344f69ae24a6b7115144d7898d14cdd1b28b5e8..8916410307f13c287fc003e1927da5dbce5ff270 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1580,35 +1580,39 @@ and is between 256 and 4096 characters. It is defined in the file
 
        slram=          [HW,MTD]
 
-       slub_debug      [MM, SLUB]
-                       Enabling slub_debug allows one to determine the culprit
-                       if slab objects become corrupted. Enabling slub_debug
-                       creates guard zones around objects and poisons objects
-                       when not in use. Also tracks the last alloc / free.
-                       For more information see Documentation/vm/slub.txt.
+       slub_debug[=options[,slabs]]    [MM, SLUB]
+                       Enabling slub_debug allows one to determine the
+                       culprit if slab objects become corrupted. Enabling
+                       slub_debug can create guard zones around objects and
+                       may poison objects when not in use. Also tracks the
+                       last alloc / free. For more information see
+                       Documentation/vm/slub.txt.
 
        slub_max_order= [MM, SLUB]
-                       Determines the maximum allowed order for slabs. Setting
-                       this too high may cause fragmentation.
-                       For more information see Documentation/vm/slub.txt.
+                       Determines the maximum allowed order for slabs.
+                       A high setting may cause OOMs due to memory
+                       fragmentation. For more information see
+                       Documentation/vm/slub.txt.
 
        slub_min_objects=       [MM, SLUB]
-                       The minimum objects per slab. SLUB will increase the
-                       slab order up to slub_max_order to generate a
-                       sufficiently big slab to satisfy the number of objects.
-                       The higher the number of objects the smaller the overhead
-                       of tracking slabs.
+                       The minimum number of objects per slab. SLUB will
+                       increase the slab order up to slub_max_order to
+                       generate a sufficiently large slab able to contain
+                       the number of objects indicated. The higher the number
+                       of objects the smaller the overhead of tracking slabs
+                       and the less frequently locks need to be acquired.
                        For more information see Documentation/vm/slub.txt.
 
        slub_min_order= [MM, SLUB]
                        Determines the mininum page order for slabs. Must be
-                       lower than slub_max_order
+                       lower than slub_max_order.
                        For more information see Documentation/vm/slub.txt.
 
        slub_nomerge    [MM, SLUB]
-                       Disable merging of slabs of similar size. May be
+                       Disable merging of slabs with similar size. May be
                        necessary if there is some reason to distinguish
-                       allocs to different slabs.
+                       allocs to different slabs. Debug options disable
+                       merging on their own.
                        For more information see Documentation/vm/slub.txt.
 
        smart2=         [HW]