linux-kernel - Re: [PATCHv2, RFC 19/30] thp, mm: split huge page on mmap file page

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Message-Id: <20130315134528.8BD83E0085@blue.fi.intel.com>
Date:	Fri, 15 Mar 2013 15:45:28 +0200 (EET)
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	Hillf Danton <dhillf@...il.com>
Cc:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Hugh Dickins <hughd@...gle.com>,
	Wu Fengguang <fengguang.wu@...el.com>, Jan Kara <jack@...e.cz>,
	Mel Gorman <mgorman@...e.de>, linux-mm@...ck.org,
	Andi Kleen <ak@...ux.intel.com>,
	Matthew Wilcox <matthew.r.wilcox@...el.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2, RFC 19/30] thp, mm: split huge page on mmap file page

Hillf Danton wrote:
> On Fri, Mar 15, 2013 at 9:29 PM, Kirill A. Shutemov
> <kirill.shutemov@...ux.intel.com> wrote:
> > Hillf Danton wrote:
> >> On Fri, Mar 15, 2013 at 1:50 AM, Kirill A. Shutemov
> >> <kirill.shutemov@...ux.intel.com> wrote:
> >> >
> >> > We are not ready to mmap file-backed tranparent huge pages.
> >> >
> >> It is not on todo list either.
> >
> > Actually, following patches implement mmap for file-backed thp and this
> > split_huge_page() will catch only fallback cases.
> >
> I wonder if the effort we pay for THP cache is nuked by mmap.

I will not be nuked after patch 30/30.

Actually, it will be splited only if process tries to map hugepage with
unsuitable alignment.

-- 
 Kirill A. Shutemov
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