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SubjectRe: [PATCH V2 4/4] hugetlbfs: document min_size mount option
On 03/18/2015 02:41 PM, Andrew Morton wrote:
> On Mon, 16 Mar 2015 16:53:29 -0700 Mike Kravetz <mike.kravetz@oracle.com> wrote:
>
>> Update documentation for the hugetlbfs min_size mount option.
>>
>> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
>> ---
>> Documentation/vm/hugetlbpage.txt | 21 ++++++++++++++-------
>> 1 file changed, 14 insertions(+), 7 deletions(-)
>>
>> diff --git a/Documentation/vm/hugetlbpage.txt b/Documentation/vm/hugetlbpage.txt
>> index f2d3a10..83c0305 100644
>> --- a/Documentation/vm/hugetlbpage.txt
>> +++ b/Documentation/vm/hugetlbpage.txt
>> @@ -267,8 +267,8 @@ call, then it is required that system administrator mount a file system of
>> type hugetlbfs:
>>
>> mount -t hugetlbfs \
>> - -o uid=<value>,gid=<value>,mode=<value>,size=<value>,nr_inodes=<value> \
>> - none /mnt/huge
>> + -o uid=<value>,gid=<value>,mode=<value>,size=<value>,min_size=<value>, \
>> + nr_inodes=<value> none /mnt/huge
>>
>> This command mounts a (pseudo) filesystem of type hugetlbfs on the directory
>> /mnt/huge. Any files created on /mnt/huge uses huge pages. The uid and gid
>> @@ -277,11 +277,18 @@ the uid and gid of the current process are taken. The mode option sets the
>> mode of root of file system to value & 01777. This value is given in octal.
>> By default the value 0755 is picked. The size option sets the maximum value of
>> memory (huge pages) allowed for that filesystem (/mnt/huge). The size is
>> -rounded down to HPAGE_SIZE. The option nr_inodes sets the maximum number of
>> -inodes that /mnt/huge can use. If the size or nr_inodes option is not
>> -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
>> -example, size=2K has the same meaning as size=2048.
>> +rounded down to HPAGE_SIZE. The min_size option sets the minimum value of
>> +memory (huge pages) allowed for the filesystem. Like the size option,
>> +min_size is rounded down to HPAGE_SIZE. At mount time, the number of huge
>> +pages specified by min_size are reserved for use by the filesystem. If
>> +there are not enough free huge pages available, the mount will fail. As
>> +huge pages are allocated to the filesystem and freed, the reserve count
>> +is adjusted so that the sum of allocated and reserved huge pages is always
>> +at least min_size. The option nr_inodes sets the maximum number of
>> +inodes that /mnt/huge can use. If the size, min_size or nr_inodes option
>> +is not provided on command line then no limits are set. For size, min_size
>> +and nr_inodes 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.
>
> Nowhere here is the reader told the units of "size". We should at
> least describe that, and maybe even rename the thing to min_bytes.
>

Ok, I will add that the size is in unit of bytes. My choice of
'min_size' as a name for the new mount option was influenced by
the existing 'size' mount option. I'm open to any suggestions
for the name of this new mount option.

--
Mike Kravetz


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