Merge Btrfs into fs/btrfs

[pandora-kernel.git] / Documentation / vm / hugetlbpage.txt

diff --git a/Documentation/vm/hugetlbpage.txt b/Documentation/vm/hugetlbpage.txt
index f962d01..ea8714f 100644 (file)
--- a/Documentation/vm/hugetlbpage.txt
+++ b/Documentation/vm/hugetlbpage.txt
@@ -77,7 +77,7 @@ memory that is preset in system at this time.  System administrators may want
 to put this command in one of the local rc init files.  This will enable the
 kernel to request huge pages early in the boot process (when the possibility
 of getting physical contiguous pages is still very high). In either
-case, adminstrators will want to verify the number of hugepages actually
+case, administrators will want to verify the number of hugepages actually
 allocated by checking the sysctl or meminfo.
 
 /proc/sys/vm/nr_overcommit_hugepages indicates how large the pool of
@@ -88,14 +88,36 @@ hugepages from the buddy allocator, if the normal pool is exhausted. As
 these surplus hugepages go out of use, they are freed back to the buddy
 allocator.
 
-Caveat: Shrinking the pool via nr_hugepages while a surplus is in effect
-will allow the number of surplus huge pages to exceed the overcommit
-value, as the pool hugepages (which must have been in use for a surplus
-hugepages to be allocated) will become surplus hugepages.  As long as
+Caveat: Shrinking the pool via nr_hugepages such that it becomes less
+than the number of hugepages in use will convert the balance to surplus
+huge pages even if it would exceed the overcommit value.  As long as
 this condition holds, however, no more surplus huge pages will be
 allowed on the system until one of the two sysctls are increased
 sufficiently, or the surplus huge pages go out of use and are freed.
 
+With support for multiple hugepage pools at run-time available, much of
+the hugepage userspace interface has been duplicated in sysfs. The above
+information applies to the default hugepage size (which will be
+controlled by the proc interfaces for backwards compatibility). The root
+hugepage control directory is
+
+       /sys/kernel/mm/hugepages
+
+For each hugepage size supported by the running kernel, a subdirectory
+will exist, of the form
+
+       hugepages-${size}kB
+
+Inside each of these directories, the same set of files will exist:
+
+       nr_hugepages
+       nr_overcommit_hugepages
+       free_hugepages
+       resv_hugepages
+       surplus_hugepages
+
+which function as described above for the default hugepage-sized case.
+
 If the user applications are going to request hugepages using mmap system
 call, then it is required that system administrator mount a file system of
 type hugetlbfs: