From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.parrot.fr ([213.41.120.202]) by canuck.infradead.org with esmtps (Exim 4.63 #1 (Red Hat Linux)) id 1HHiYd-0002zf-Vq for linux-mtd@lists.infradead.org; Thu, 15 Feb 2007 10:30:07 -0500 Received: from [172.20.2.179] (40.107.210.62.te-dns.org [62.210.107.40]) by smtp.parrot.fr (Postfix) with ESMTP id 72F835C30 for ; Thu, 15 Feb 2007 16:31:01 +0100 (CET) Message-ID: <45D47C92.8080908@parrot.fr> Date: Thu, 15 Feb 2007 16:30:26 +0100 From: Matthieu CASTET MIME-Version: 1.0 To: linux-mtd@lists.infradead.org Subject: jffs2 Erase Block Summary overhead Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi, after doing some test on a 64MB nand flash, we see that only 50 MB can be stored on the filesystem [1]. The extra 10 MB are taken by jffs2 summary. If we disable jffs2 sumary in the kernel, the 10MB become available. Is there a way to reduce this overhead ? 20 % seems really big. May be Centralized Summary [3] give better result ? What is its status ? Matthieu [1] # time mount /dev/mtdblock3 -t jffs2 /tmp/mnt/ ; time cat /tmp/mnt/root/file.1 > /dev/null ; du -sh /tmp/mnt; df real 0m 3.05s user 0m 0.00s sys 0m 3.05s real 0m 0.34s user 0m 0.01s sys 0m 0.33s 50.6M /tmp/mnt Filesystem Size Used Available Use% Mounted on /dev/mtdblock3 61.5M 60.7M 832.0k 99% /tmp/mnt [2] # time mount /dev/mtdblock3 -t jffs2 /tmp/mnt/ ; time cat /tmp/mnt/root/file.1 > /dev/null ; du -sh /tmp/mnt; df real 0m 11.30s user 0m 0.01s sys 0m 11.28s real 0m 0.35s user 0m 0.00s sys 0m 0.33s 50.6M /tmp/mnt /dev/mtdblock3 61.5M 51.2M 10.3M 83% /tmp/mnt [3] http://www.inf.u-szeged.hu/jffs2/mount.php