From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [222.66.49.139] (helo=smailsh.E28.COM) by canuck.infradead.org with esmtp (Exim 4.54 #1 (Red Hat Linux)) id 1Eejys-0002Pu-12 for linux-mtd@lists.infradead.org; Tue, 22 Nov 2005 21:03:36 -0500 From: kevinwu To: Ferenc Havasi In-Reply-To: <438322C6.6020002@inf.u-szeged.hu> References: <1132624224.3577.15.camel@localhost.localdomain> <438322C6.6020002@inf.u-szeged.hu> Content-Type: text/plain; charset=utf-8 Date: Wed, 23 Nov 2005 09:57:33 +0800 Message-Id: <1132711053.3539.25.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Cc: linux-mtd@lists.infradead.org Subject: Re: small erase block size with EBS List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Ferenc, I successfully mounted a 128KiB erase block size summary image on a 16KiB erase block size NAND. The mounting speed is very high. It takes only about 0.5 second mounting on a 32MiB partition with 90% disk full.(My cpu is ARM926 running at 201 MHz) It seems OK. The performance is good. I modified JFFS2 source code a little. I changed souce code in function jffs2_do_fill_super() from: c->sector_size =3D c->mtd->size; to: c->sector_size =3D 0x00020000; //erase block size of image you generated.=20 It does work if the jffs2 partition has no bad block. If there is a bad block, it will get error imformation. But I will fix this bug soon. I know what happend.=20 =E5=9C=A8 2005-11-22=E4=BA=8C=E7=9A=84 14:53 +0100=EF=BC=8CFerenc Havasi=E5= =86=99=E9=81=93=EF=BC=9A > Hi, >=20 > > I have a NAND flash with a small erase block(16KiB) > > When I use sumtool, I find that the summary image size is much larger > > than the original one if I use option --eraseblock=3D0x4000. > > But When I use option --eraseblock=3D0x20000, The summary image is a bi= t > > larger than the original one. > > EBS fits for large erase block as far as I know.=20 > > That is to say, I can not use EBS if the NAND erase block is small. Wha= t > > a pitty! > > Is there any way to use EBS on a small erase block size NAND? >=20 > EBS should work on your system but if the erase block size is small it=20 > may be not too usefull. Generally if you use bigger erase block size the=20 > speedup will be greater and the "used place penalty" will be smaller. >=20 > So I suggest to test it: measure the rete of speedup and the difference=20 > in image size on your system, and you can decide it is OK for you or not. >=20 > > What about CS? >=20 > CS doesn't depend on erase block size as EBS does, so you may try it.=20 > The code of CS is more then one mouth old, so you should use it with=20 > earlier mtd snapshot. If you can wait a little we will update it at the=20 > first week of december. It seems a better choise. I will try it. Thanks for your information. --=20 Best Regards Kevin Wu System Software Engineer, E28.com Office: 86-21-23060088-352