linux-kernel - Re: [PATCH -mm v5 12/13] mm: /proc/pid/clear_refs: avoid split_huge

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Message-ID: <20140714064019.GF19702@moon>
Date:	Mon, 14 Jul 2014 10:40:19 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc:	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	Dave Hansen <dave.hansen@...el.com>,
	Hugh Dickins <hughd@...gle.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	Jerome Marchand <jmarchan@...hat.com>,
	linux-kernel@...r.kernel.org,
	Naoya Horiguchi <nao.horiguchi@...il.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: [PATCH -mm v5 12/13] mm: /proc/pid/clear_refs: avoid
 split_huge_page()

On Fri, Jul 11, 2014 at 02:35:48PM -0400, Naoya Horiguchi wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
> 
> Currently pagewalker splits all THP pages on any clear_refs request.  It's
> not necessary.  We can handle this on PMD level.
> 
> One side effect is that soft dirty will potentially see more dirty memory,
> since we will mark whole THP page dirty at once.
> 
> Sanity checked with CRIU test suite. More testing is required.
> 
> ChangeLog:
> - move code for thp to clear_refs_pte_range()
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> Cc: Pavel Emelyanov <xemul@...allels.com>
> Cc: Andrea Arcangeli <aarcange@...hat.com>
> Cc: Dave Hansen <dave.hansen@...el.com>
> Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
> Cc: Cyrill Gorcunov <gorcunov@...il.com>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Reviewed-by: Cyrill Gorcunov <gorcunov@...nvz.org>
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