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Date: Fri, 28 Feb 2014 02:18:58 +0200
From: "Kirill A. Shutemov" <kirill@shutemov.name>
Subject: Re: [PATCHv3 1/2] mm: introduce vm_ops->map_pages()
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To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>, Andi Kleen <ak@linux.intel.com>, Matthew Wilcox <matthew.r.wilcox@intel.com>, Alexander Viro <viro@zeniv.linux.org.uk>, Dave Chinner <david@fromorbit.com>, Ning Qu <quning@gmail.com>, linux-mm <linux-mm@kvack.org>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, anton@samba.org, Paul Mackerras <paulus@samba.org>, Benjamin Herrenschmidt <benh@kernel.crashing.org>

On Thu, Feb 27, 2014 at 02:34:55PM -0800, Dave Hansen wrote:
> Kirill's git test suite runs did show that it _can_ hurt in some cases.

And see last use-case for how much it can hurt. :)

It shouldn't differs much for the same *number* of pages between [u]archs
unless setup of the pte is significantly more expensive or page fault is
faster.

But of course, I can move FAULT_AROUND_PAGES to arch/x86/ and let
architecture mantainers to decide if they want the feature. ;)

-- 
 Kirill A. Shutemov

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