linux-kernel - Re: [00/41] Large Blocksize Support V7 (adds memmap support)

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Message-ID: <Pine.LNX.4.64.0709171501520.29993@schroedinger.engr.sgi.com>
Date:	Mon, 17 Sep 2007 15:03:07 -0700 (PDT)
From:	Christoph Lameter <clameter@....com>
To:	Jörn Engel <joern@...fs.org>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Nick Piggin <nickpiggin@...oo.com.au>, andrea@...e.de,
	torvalds@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, Christoph Hellwig <hch@....de>,
	Mel Gorman <mel@...net.ie>,
	William Lee Irwin III <wli@...omorphy.com>,
	David Chinner <dgc@....com>,
	Jens Axboe <jens.axboe@...cle.com>,
	Badari Pulavarty <pbadari@...il.com>,
	Maxim Levitsky <maximlevitsky@...il.com>,
	Fengguang Wu <fengguang.wu@...il.com>,
	swin wang <wangswin@...il.com>, totty.lu@...il.com,
	hugh@...itas.com
Subject: Re: [00/41] Large Blocksize Support V7 (adds memmap support)

On Sun, 16 Sep 2007, Jörn Engel wrote:

> I bet!  My (false) assumption was the same as Goswin's.  If non-movable
> pages are clearly seperated from movable ones and will evict movable
> ones before polluting further mixed superpages, Nick's scenario would be
> nearly infinitely impossible.
> 
> Assumption doesn't reflect current code.  Enforcing this assumption
> would cost extra overhead.  The amount of effort to make Christoph's
> approach work reliably seems substantial and I have no idea whether it
> would be worth it.

My approach is based on Mel's code and is already working the way you 
describe. Page cache allocs are marked __GFP_MOVABLE by Mel's work.