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Date: Fri, 2 Sep 2011 03:17:16 +0200
From: Andi Kleen <andi@firstfloor.org>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Minchan Kim <minchan.kim@gmail.com>,
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        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Shaohua Li <shaohua.li@intel.com>,
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Subject: Re: [PATCH] thp: tail page refcounting fix #5
Message-ID: <20110902011716.GE7761@one.firstfloor.org>
References: <20110826062436.GA5847@google.com> <20110826161048.GE23870@redhat.com> <20110826185430.GA2854@redhat.com> <20110827094152.GA16402@google.com> <20110827173421.GA2967@redhat.com> <CAEwNFnDk0bQZKReKccuQMPEw_6EA2DxN4dm9cmjr01BVT4A7Dw@mail.gmail.com> <20110901152417.GF10779@redhat.com> <20110901162808.80a2117c.akpm@linux-foundation.org> <20110901234527.GD7761@one.firstfloor.org> <20110902002013.GJ10779@redhat.com>
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> Calling get_page/put_pages more times than necessary is never ideal, I
> imagine the biggest cost is the atomic_inc on the head page that

I've actually seen it in profile logs, but I hadn't realized it was redundant.

Have to see if it brings a benefit to hot users.

-Andi