Re: [PATCH] mm/hugetlb: optimize minimum size (min_size) accounting

[Naoya Horiguchi]

On Fri, Mar 25, 2016 at 04:44:58PM -0700, Mike Kravetz wrote:
> It was observed that minimum size accounting associated with the
> hugetlbfs min_size mount option may not perform optimally and as
> expected.  As huge pages/reservations are released from the filesystem
> and given back to the global pools, they are reserved for subsequent
> filesystem use as long as the subpool reserved count is less than
> subpool minimum size.  It does not take into account used pages
> within the filesystem.  The filesystem size limits are not exceeded
> and this is technically not a bug.  However, better behavior would
> be to wait for the number of used pages/reservations associated with
> the filesystem to drop below the minimum size before taking reservations
> to satisfy minimum size.
> 
> An optimization is also made to the hugepage_subpool_get_pages()
> routine which is called when pages/reservations are allocated.  This
> does not change behavior, but simply avoids the accounting if all
> reservations have already been taken (subpool reserved count == 0).
> 
> Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>

Seems OK to me.

Acked-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>