linux-kernel - Re: [PATCHv3 1/2] mm: introduce vm_ops->map

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Message-ID: <20140228001858.GC8034@node.dhcp.inet.fi>
Date:	Fri, 28 Feb 2014 02:18:58 +0200
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Dave Hansen <dave.hansen@...ux.intel.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Matthew Wilcox <matthew.r.wilcox@...el.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Dave Chinner <david@...morbit.com>, Ning Qu <quning@...il.com>,
	linux-mm <linux-mm@...ck.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	anton@...ba.org, Paul Mackerras <paulus@...ba.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [PATCHv3 1/2] mm: introduce vm_ops->map_pages()

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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