Re: [PATCH V2 4/4] hugetlbfs: document min_size mount option

[Mike Kravetz]

On 03/18/2015 02:41 PM, Andrew Morton wrote:
> On Mon, 16 Mar 2015 16:53:29 -0700 Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote:
>
> > Update documentation for the hugetlbfs min_size mount option.
> >
> > Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> > ---
> >   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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