From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ug-out-1314.google.com ([66.249.92.171]) by canuck.infradead.org with esmtp (Exim 4.62 #1 (Red Hat Linux)) id 1GitaS-0003Af-92 for linux-mtd@lists.infradead.org; Sat, 11 Nov 2006 09:12:07 -0500 Received: by ug-out-1314.google.com with SMTP id m2so744852uge for ; Sat, 11 Nov 2006 06:11:57 -0800 (PST) Message-ID: <6d6a94c50611110611j2d1bce01p9e227e2ff5bc1bae@mail.gmail.com> Date: Sat, 11 Nov 2006 22:11:56 +0800 From: Aubrey To: dedekind@infradead.org Subject: Re: mount costs too long In-Reply-To: <1163178941.3925.18.camel@sauron> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <6d6a94c50611092305v6f52b9b0hfd254e10a2992d44@mail.gmail.com> <1163159781.19697.24.camel@crusty.rchland.ibm.com> <6d6a94c50611100648g87770a0qb723fad11fa65cd8@mail.gmail.com> <1163174898.3925.13.camel@sauron> <4554A592.5000308@ru.mvista.com> <1163176000.3925.15.camel@sauron> <4554AA07.5020204@ru.mvista.com> <1163178941.3925.18.camel@sauron> Cc: linux-mtd@lists.infradead.org, Vitaly Wool List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 11/11/06, Artem Bityutskiy wrote: > On Fri, 2006-11-10 at 19:34 +0300, Vitaly Wool wrote: > > B/c due to the MTD layer rework, there's no way now to use custom > > oobinfo in yaffs. > > Therefore, as yaffs1 presumes the SmartMedia OOB layout one can either > > read/write raw OOB but that will most probably break the bad block > > handling, or implement a small shim layer putting spare OOB area into > > SmartMedia OOB layout or back. Any other way will result in > > incompatibility with the older version of yaffs1. > > OK, as it was said that YAFFS1 becomes much slower, this means that it > reads more data from OOB then if it were working with older kernel. > Right? Why it reads more data? > Well, If I understand correctly, this should be a YAFFS issue. I got the following explaination from YAFFS mailing list: ------------------ Charles Manning to yaffs, me On Saturday 11 November 2006 03:53, Vitaly Wool wrote: > You'll have to do some code hacking to speed things up. I.e. you'll > need to set up your OOB layout according to SmartMedia spec and then > you'll be able to remove the translation shim in yaffs code. It is important to understand this: The mtd NAND driver is generic code that is parameterised by configuration tables to make it flexible. This gives an (almost/often) out of the box experience, and IMHO, is pretty slick code, but there's a cost associated with the flexibility. A custom driver can be a lot faster, but then it won't be generic any more. Most people who want fast NAND speed end up writing their own custom drivers to maximise ransfer with their hardware. --------------------- I think I need more time to read source code to understand this. Did anyone enable yaffs on small page NAND chip on the kernel >= 2.6.18? -Aubrey