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Date: Tue, 20 May 2014 00:32:01 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH V4 0/2] mm: FAULT_AROUND_ORDER patchset performance data
 for powerpc
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Cc: linux-arch@vger.kernel.org, riel@redhat.com,
 Madhavan Srinivasan <maddy@linux.vnet.ibm.com>, dave.hansen@intel.com,
 peterz@infradead.org, x86@kernel.org, Hugh Dickins <hughd@google.com>,
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 paulus@samba.org, mgorman@suse.de, linuxppc-dev@lists.ozlabs.org,
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On Tue, 20 May 2014 15:52:07 +0930 Rusty Russell <rusty@rustcorp.com.au> wrote:

> "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> writes:
> > Andrew Morton wrote:
> >> On Mon, 19 May 2014 16:23:07 -0700 (PDT) Hugh Dickins <hughd@google.com> wrote:
> >> 
> >> > Shouldn't FAULT_AROUND_ORDER and fault_around_order be changed to be
> >> > the order of the fault-around size in bytes, and fault_around_pages()
> >> > use 1UL << (fault_around_order - PAGE_SHIFT)
> >> 
> >> Yes.  And shame on me for missing it (this time!) at review.
> >> 
> >> There's still time to fix this.  Patches, please.
> >
> > Here it is. Made at 3.30 AM, build tested only.
> 
> Prefer on top of Maddy's patch which makes it always a variable, rather
> than CONFIG_DEBUG_FS.  It's got enough hair as it is.
> 

We're at 3.15-rc5 and this interface should be finalised for 3.16.  So
Kirrill's patch is pretty urgent and should come first.

Well.  It's only a debugfs interface at this stage so we are allowed to
change it later, but it's better not to.