linux-kernel - Re: [PATCH -mm -v10 3/3] mm, THP, swap: Enable THP swap optimization only if has compound map

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Message-ID: <20170428131628.vsiapdgm7e6yddsb@node.shutemov.name>
Date:   Fri, 28 Apr 2017 16:16:28 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Johannes Weiner <hannes@...xchg.org>
Cc:     "Huang, Ying" <ying.huang@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH -mm -v10 3/3] mm, THP, swap: Enable THP swap optimization
 only if has compound map

On Tue, Apr 25, 2017 at 05:46:18PM -0400, Johannes Weiner wrote:
> On Tue, Apr 25, 2017 at 08:56:58PM +0800, Huang, Ying wrote:
> > From: Huang Ying <ying.huang@...el.com>
> > 
> > If there is no compound map for a THP (Transparent Huge Page), it is
> > possible that the map count of some sub-pages of the THP is 0.  So it
> > is better to split the THP before swapping out. In this way, the
> > sub-pages not mapped will be freed, and we can avoid the unnecessary
> > swap out operations for these sub-pages.
> > 
> > Cc: Johannes Weiner <hannes@...xchg.org>
> > Signed-off-by: "Huang, Ying" <ying.huang@...el.com>
> 
> Acked-by: Johannes Weiner <hannes@...xchg.org>
> 
> CC Kirill to double check the reasoning here

Looks good to me:

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

-- 
 Kirill A. Shutemov