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Date: Thu, 26 Aug 2004 17:18:40 -0700
From: Andrew Morton <akpm@osdl.org>
To: Hiroyuki KAMEZAWA <kamezawa.hiroyu@jp.fujitsu.com>
Cc: haveblue@us.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
       lhms-devel@lists.sourceforge.net, wli@holomorphy.com
Subject: Re: [Lhms-devel] [RFC] buddy allocator without bitmap  [2/4]
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Hiroyuki KAMEZAWA <kamezawa.hiroyu@jp.fujitsu.com> wrote:
>
> In the previous version, I used SetPagePrivate()/ClearPagePrivate()/PagePrivate().
> But these are "atomic" operation and looks very slow.
> This is why I doesn't used these macros in this version.
> 
> My previous version, which used set_bit/test_bit/clear_bit, shows very bad performance
> on my test, and I replaced it.

That's surprising.  But if you do intend to use non-atomic bitops then
please add __SetPagePrivate() and __ClearPagePrivate()