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From: Phillip Lougher <phillip@lougher.demon.co.uk>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Zero-clearing all zero-clearable bytes.
Date: Sun, 23 Nov 2008 04:27:27 +0000	[thread overview]
Message-ID: <4928DBAF.4030209@lougher.demon.co.uk> (raw)
In-Reply-To: <200811221236.FJE81778.LtMHOQFJFVFSOO@I-love.SAKURA.ne.jp>

Tetsuo Handa wrote:
> Hello.
> 
> I often create a Live CD.
> When creating a Live CD, loopback mounted ext3 image files are used.
> These image files are then compressed so that the ISO image will fit within
> a CD-R's capacity (i.e. 700MB).
> 

You don't mention what you're using to compress the ext3 image file.  If 
you're using Squashfs then it's much better to zero-fill the blocks 
rather than use 255, because Squashfs detects zero-filled blocks and 
stores them sparsely.  This not only gets slightly better compression 
(than a compressed zero-filled block), but reading is also slightly faster.

Phillip



  parent reply	other threads:[~2008-11-23  4:27 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-22  3:36 Zero-clearing all zero-clearable bytes Tetsuo Handa
2008-11-22 17:44 ` Andreas Dilger
2008-11-23  0:15   ` Tetsuo Handa
2008-11-23  3:05     ` Phillip Lougher
2008-11-23  4:27 ` Phillip Lougher [this message]
2008-11-23  5:03   ` Tetsuo Handa
2008-11-23 11:25     ` Henrique de Moraes Holschuh
2008-11-24 14:56       ` Martin Steigerwald
2008-11-25 10:59         ` Tetsuo Handa

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