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-rw-r--r--Documentation/vm/hugetlbpage.txt20
1 files changed, 10 insertions, 10 deletions
diff --git a/Documentation/vm/hugetlbpage.txt b/Documentation/vm/hugetlbpage.txt
index 1ad9af1ca4d0..2803f63c1a27 100644
--- a/Documentation/vm/hugetlbpage.txt
+++ b/Documentation/vm/hugetlbpage.txt
@@ -27,7 +27,7 @@ number of free hugetlb pages at any time. It also displays information about
27the configured hugepage size - this is needed for generating the proper 27the configured hugepage size - this is needed for generating the proper
28alignment and size of the arguments to the above system calls. 28alignment and size of the arguments to the above system calls.
29 29
30The output of "cat /proc/meminfo" will have output like: 30The output of "cat /proc/meminfo" will have lines like:
31 31
32..... 32.....
33HugePages_Total: xxx 33HugePages_Total: xxx
@@ -42,11 +42,11 @@ pages in the kernel. Super user can dynamically request more (or free some
42pre-configured) hugepages. 42pre-configured) hugepages.
43The allocation (or deallocation) of hugetlb pages is possible only if there are 43The allocation (or deallocation) of hugetlb pages is possible only if there are
44enough physically contiguous free pages in system (freeing of hugepages is 44enough physically contiguous free pages in system (freeing of hugepages is
45possible only if there are enough hugetlb pages free that can be transfered 45possible only if there are enough hugetlb pages free that can be transferred
46back to regular memory pool). 46back to regular memory pool).
47 47
48Pages that are used as hugetlb pages are reserved inside the kernel and can 48Pages that are used as hugetlb pages are reserved inside the kernel and cannot
49not be used for other purposes. 49be used for other purposes.
50 50
51Once the kernel with Hugetlb page support is built and running, a user can 51Once the kernel with Hugetlb page support is built and running, a user can
52use either the mmap system call or shared memory system calls to start using 52use either the mmap system call or shared memory system calls to start using
@@ -60,7 +60,7 @@ Use the following command to dynamically allocate/deallocate hugepages:
60This command will try to configure 20 hugepages in the system. The success 60This command will try to configure 20 hugepages in the system. The success
61or failure of allocation depends on the amount of physically contiguous 61or failure of allocation depends on the amount of physically contiguous
62memory that is preset in system at this time. System administrators may want 62memory that is preset in system at this time. System administrators may want
63to put this command in one of the local rc init file. This will enable the 63to put this command in one of the local rc init files. This will enable the
64kernel to request huge pages early in the boot process (when the possibility 64kernel to request huge pages early in the boot process (when the possibility
65of getting physical contiguous pages is still very high). 65of getting physical contiguous pages is still very high).
66 66
@@ -78,8 +78,8 @@ the uid and gid of the current process are taken. The mode option sets the
78mode of root of file system to value & 0777. This value is given in octal. 78mode of root of file system to value & 0777. This value is given in octal.
79By default the value 0755 is picked. The size option sets the maximum value of 79By default the value 0755 is picked. The size option sets the maximum value of
80memory (huge pages) allowed for that filesystem (/mnt/huge). The size is 80memory (huge pages) allowed for that filesystem (/mnt/huge). The size is
81rounded down to HPAGE_SIZE. The option nr_inode sets the maximum number of 81rounded down to HPAGE_SIZE. The option nr_inodes sets the maximum number of
82inodes that /mnt/huge can use. If the size or nr_inode options are not 82inodes that /mnt/huge can use. If the size or nr_inodes options are not
83provided on command line then no limits are set. For size and nr_inodes 83provided on command line then no limits are set. For size and nr_inodes
84options, you can use [G|g]/[M|m]/[K|k] to represent giga/mega/kilo. For 84options, you can use [G|g]/[M|m]/[K|k] to represent giga/mega/kilo. For
85example, size=2K has the same meaning as size=2048. An example is given at 85example, size=2K has the same meaning as size=2048. An example is given at
@@ -88,7 +88,7 @@ the end of this document.
88read and write system calls are not supported on files that reside on hugetlb 88read and write system calls are not supported on files that reside on hugetlb
89file systems. 89file systems.
90 90
91A regular chown, chgrp and chmod commands (with right permissions) could be 91Regular chown, chgrp, and chmod commands (with right permissions) could be
92used to change the file attributes on hugetlbfs. 92used to change the file attributes on hugetlbfs.
93 93
94Also, it is important to note that no such mount command is required if the 94Also, it is important to note that no such mount command is required if the
@@ -96,8 +96,8 @@ applications are going to use only shmat/shmget system calls. Users who
96wish to use hugetlb page via shared memory segment should be a member of 96wish to use hugetlb page via shared memory segment should be a member of
97a supplementary group and system admin needs to configure that gid into 97a supplementary group and system admin needs to configure that gid into
98/proc/sys/vm/hugetlb_shm_group. It is possible for same or different 98/proc/sys/vm/hugetlb_shm_group. It is possible for same or different
99applications to use any combination of mmaps and shm* calls. Though the 99applications to use any combination of mmaps and shm* calls, though the
100mount of filesystem will be required for using mmaps. 100mount of filesystem will be required for using mmap calls.
101 101
102******************************************************************* 102*******************************************************************
103 103