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[PATCH] perform maintenance on Documentation/vm/hugetlbpage.txt

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Updates to Documentation/vm/hugetlbpage.txt:

- there's no need to select HUGETLB_PAGE manually and it's no longer
  under the processor menu.  Update the text accordingly.

- fix typos and trim trailing whitespace.

Signed-Off-By: Muli Ben-Yehuda <mulix@mulix.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Muli Ben-Yehuda
2005-11-07 00:59:42 -08:00
committed by Linus Torvalds
parent 385fd4c59d
commit 5c7ad5104d
1 changed files with 13 additions and 12 deletions
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Documentation/vm/hugetlbpage.txt
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@@ -13,12 +13,13 @@ This optimization is more critical now as bigger and bigger physical memories
Users can use the huge page support in Linux kernel by either using the mmap Users can use the huge page support in Linux kernel by either using the mmap
system call or standard SYSv shared memory system calls (shmget, shmat). system call or standard SYSv shared memory system calls (shmget, shmat).
First the Linux kernel needs to be built with CONFIG_HUGETLB_PAGE (present First the Linux kernel needs to be built with the CONFIG_HUGETLBFS
under Processor types and feature) and CONFIG_HUGETLBFS (present under file (present under "File systems") and CONFIG_HUGETLB_PAGE (selected
system option on config menu) config options. automatically when CONFIG_HUGETLBFS is selected) configuration
options.
The kernel built with hugepage support should show the number of configured The kernel built with hugepage support should show the number of configured
hugepages in the system by running the "cat /proc/meminfo" command. hugepages in the system by running the "cat /proc/meminfo" command.
/proc/meminfo also provides information about the total number of hugetlb /proc/meminfo also provides information about the total number of hugetlb
pages configured in the kernel. It also displays information about the pages configured in the kernel. It also displays information about the
@@ -38,19 +39,19 @@ in the kernel.
/proc/sys/vm/nr_hugepages indicates the current number of configured hugetlb /proc/sys/vm/nr_hugepages indicates the current number of configured hugetlb
pages in the kernel. Super user can dynamically request more (or free some pages in the kernel. Super user can dynamically request more (or free some
pre-configured) hugepages. pre-configured) hugepages.
The allocation( or deallocation) of hugetlb pages is posible only if there are The allocation (or deallocation) of hugetlb pages is possible only if there are
enough physically contiguous free pages in system (freeing of hugepages is enough physically contiguous free pages in system (freeing of hugepages is
possible only if there are enough hugetlb pages free that can be transfered possible only if there are enough hugetlb pages free that can be transfered
back to regular memory pool). back to regular memory pool).
Pages that are used as hugetlb pages are reserved inside the kernel and can Pages that are used as hugetlb pages are reserved inside the kernel and can
not be used for other purposes. not be used for other purposes.
Once the kernel with Hugetlb page support is built and running, a user can Once the kernel with Hugetlb page support is built and running, a user can
use either the mmap system call or shared memory system calls to start using use either the mmap system call or shared memory system calls to start using
the huge pages. It is required that the system administrator preallocate the huge pages. It is required that the system administrator preallocate
enough memory for huge page purposes. enough memory for huge page purposes.
Use the following command to dynamically allocate/deallocate hugepages: Use the following command to dynamically allocate/deallocate hugepages:
@@ -80,9 +81,9 @@ memory (huge pages) allowed for that filesystem (/mnt/huge). The size is
rounded down to HPAGE_SIZE. The option nr_inode sets the maximum number of rounded down to HPAGE_SIZE. The option nr_inode sets the maximum number of
inodes that /mnt/huge can use. If the size or nr_inode options are not inodes that /mnt/huge can use. If the size or nr_inode options are not
provided on command line then no limits are set. For size and nr_inodes provided on command line then no limits are set. For size and nr_inodes
options, you can use [G|g]/[M|m]/[K|k] to represent giga/mega/kilo. For options, you can use [G|g]/[M|m]/[K|k] to represent giga/mega/kilo. For
example, size=2K has the same meaning as size=2048. An example is given at example, size=2K has the same meaning as size=2048. An example is given at
the end of this document. the end of this document.
read and write system calls are not supported on files that reside on hugetlb read and write system calls are not supported on files that reside on hugetlb
file systems. file systems.