From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fk-out-0910.google.com ([209.85.128.185]) by bombadil.infradead.org with esmtp (Exim 4.69 #1 (Red Hat Linux)) id 1LU8Sp-0003EQ-AQ for linux-mtd@lists.infradead.org; Mon, 02 Feb 2009 23:44:30 +0000 Received: by fk-out-0910.google.com with SMTP id z23so1539469fkz.2 for ; Mon, 02 Feb 2009 15:44:25 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <4986D677.3020500@nokia.com> References: <31956721.196931233319535527.JavaMail.weblogic@epml10> <1233567078.7085.62.camel@localhost.localdomain> <618F1BB69C6C43C895C260C527C4F159@sisodomain.com> <4986D3F6.5030208@nokia.com> <1233572259.7085.64.camel@localhost.localdomain> <4986D677.3020500@nokia.com> Date: Tue, 3 Feb 2009 00:44:25 +0100 Message-ID: <71cd59b00902021544w594d4acandc0183bc523aafb0@mail.gmail.com> Subject: Re: Regarding UBI scalability From: Corentin Chary To: Adrian Hunter Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Amit Kumar Sharma , "linux-mtd@lists.infradead.org" , "brij.singh@samsung.com" List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, Feb 2, 2009 at 12:18 PM, Adrian Hunter wrote: > Artem Bityutskiy wrote: >> On Mon, 2009-02-02 at 13:07 +0200, Adrian Hunter wrote: >>> I would suggest an intermediate step. Create UBI2 which is >>> similar to UBI but stores eraseblock information in one place, >>> instead of at the beginning of each eraseblock. Such an approach >>> might be OK up to as much as 64GiB, and would probably perform >>> better than a fully scalable version. >>> >>> Then look at creating UBI3, which is fully scalable. >> >> Yes, I assume UBI2 should store mapping/erasure information in separate >> tables, not in each eraseblock. So we should get rid of eraseblock >> headers. > > Yes that is what I meant. You could probably make do with as little as > 12 bytes per eraseblock so a 64GiB flash with 512KiB eraseblock size > would need 1536KiB table, which could be read in a second or two, so > mount time is OK. Hi, I was wondering how it is possible to get atomic operations using such tables ? The first thing that come to my mind is TFAT (two tables, one for operation in progress, the other considered as always "valid"). But I'm not sure it' the good way to do such a thing. -- Corentin Chary http://xf.iksaif.net