linux-kernel - Re: [PATCH] mm/hugetlb: optimize minimum size (min

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Date:	Thu, 31 Mar 2016 01:00:03 +0000
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Mike Kravetz <mike.kravetz@...cle.com>
CC:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Hillf Danton <hillf.zj@...baba-inc.com>,
	David Rientjes <rientjes@...gle.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: Re: [PATCH] mm/hugetlb: optimize minimum size (min_size) accounting

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@...cle.com>

Seems OK to me.

Acked-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>