From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Hugh Dickins <hughd@google.com>, Rik van Riel <riel@redhat.com>,
Hillf Danton <dhillf@gmail.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Naoya Horiguchi <nao.horiguchi@gmail.com>
Subject: Re: [PATCH] rmap: fix pgoff calculation to handle hugepage correctly
Date: Tue, 1 Jul 2014 23:15:40 +0300 [thread overview]
Message-ID: <20140701201540.GA5953@node.dhcp.inet.fi> (raw)
In-Reply-To: <20140701185021.GA10356@nhori.bos.redhat.com>
On Tue, Jul 01, 2014 at 02:50:21PM -0400, Naoya Horiguchi wrote:
> On Tue, Jul 01, 2014 at 09:07:39PM +0300, Kirill A. Shutemov wrote:
> > Why do we need this special case for hugetlb page ->index? Why not use
> > PAGE_SIZE units there too? Or I miss something?
>
> hugetlb pages are never split, so we use larger page cache size for
> hugetlbfs file (to avoid large sparse page cache tree.)
For transparent huge page cache I would like to have native support in
page cache radix-tree: since huge pages are always naturally aligned we
can create a leaf node for it several (RADIX_TREE_MAP_SHIFT -
HPAGE_PMD_ORDER) levels up by tree, which would cover all indexes in the
range the huge page represents. This approach should fit hugetlb too. And
-1 special case for hugetlb.
But I'm not sure when I'll get time to play with this...
--
Kirill A. Shutemov
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next prev parent reply other threads:[~2014-07-01 20:15 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-01 14:46 [PATCH] rmap: fix pgoff calculation to handle hugepage correctly Naoya Horiguchi
2014-07-01 17:42 ` Rik van Riel
2014-07-01 18:07 ` Kirill A. Shutemov
2014-07-01 18:50 ` Naoya Horiguchi
2014-07-01 20:15 ` Kirill A. Shutemov [this message]
2014-07-02 4:30 ` Naoya Horiguchi
2014-07-03 11:41 ` Kirill A. Shutemov
2014-07-07 19:39 ` Andrew Morton
2014-07-15 16:41 ` [PATCH -mm] mm: refactor page index/offset getters Naoya Horiguchi
2014-07-23 21:39 ` Andrew Morton
2014-07-23 21:45 ` Naoya Horiguchi
2014-07-28 20:29 ` Johannes Weiner
2014-07-29 0:42 ` Naoya Horiguchi
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