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

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Date:	Tue, 18 Sep 2007 12:49:49 +0200
From:	Jörn Engel <joern@...fs.org>
To:	Mel Gorman <mel@...net.ie>
Cc:	Christoph Lameter <clameter@....com>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Goswin von Brederlow <brederlo@...ormatik.uni-tuebingen.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Joern Engel <joern@...fs.org>, andrea@...e.de,
	torvalds@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, Christoph Hellwig <hch@....de>,
	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 Tue, 18 September 2007 11:00:40 +0100, Mel Gorman wrote:
> 
> We still lack data on what sort of workloads really benefit from large
> blocks

Compressing filesystems like jffs2 and logfs gain better compression
ratio with larger blocks.  Going from 4KiB to 64KiB gave somewhere
around 10% benefit iirc.  Testdata was a 128MiB qemu root filesystem.

Granted, the same could be achieved by adding some extra code and a few
bounce buffers to the filesystem.  How suck a hack would perform I'd
prefer not to find out, though. :)

Jörn

-- 
Write programs that do one thing and do it well. Write programs to work
together. Write programs to handle text streams, because that is a
universal interface.
-- Doug MacIlroy
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