From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [213.170.72.194] (helo=shelob.oktetlabs.ru) by canuck.infradead.org with esmtp (Exim 4.42 #1 (Red Hat Linux)) id 1CKWSG-0003Dg-Jb for linux-mtd@lists.infradead.org; Thu, 21 Oct 2004 02:29:46 -0400 Message-ID: <41775737.9080203@yandex.ru> Date: Thu, 21 Oct 2004 10:29:11 +0400 From: "Artem B. Bityuckiy" MIME-Version: 1.0 To: Ferenc Havasi References: <41767593.9030004@inf.u-szeged.hu> In-Reply-To: <41767593.9030004@inf.u-szeged.hu> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: dwmw2@infradead.org, linux-mtd@lists.infradead.org, jffs-dev@axis.com Subject: Re: JFFS2 mount time List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hello Ferenc, As I understand, you only prepare JFFS2 image with summaries. This is great until we do not change anything. For read-only file-systems this is OK. But what if files/direntries are changed/deleted ? Do you write summary information dynamically? How are you going to place nodes/direntries to different blocks dynamically? Ferenc Havasi wrote: > Dear All, > > Here is the latest version of our mount time improvement. > > Using of it: > - apply this patch on the latest version of MTD > - compile sumtool (make command in mtd/util) > - make your JFFS2 image as before (or you can use already created images > as well) > - run sumtool to insert summary information, for example: > ./sumtool -i original.jffs2 -o new.jffs2 -e128KiB > - recompile your kernel with "JFFS2 inode summary support" > > Jarkko made a measurement on a real NAND device: his JFFS2 image was > 120819928 (115M), after running sumtool the new image was 123338752 (117M). > > Using the original mount time was 55 sec, with the new image it is only > 8.5 sec. > > It works very similar as our previous improvement: stores special > information at the end of the erase blocks, and at mount time if there > is this kind of information the scaning of the erase block is unneccessary. > > New things compared to our previous improvement: > - it was fully rewritten > - we separated the user space tool from mkfs. (sumtool) > - sumtool now not only inserts the summary information but also make > some node-reordering. There will be two kind of erase blocks: in the > "first type" there will be only jffs2_raw_inodes, and all other node > (jffs2_raw_dirent) will be stored in the "second type". It generates > summary at the end of all "fist type" eraseblock. (the "second type" > will be scanned as before, because all information is needed in > jffs_raw_dirent at mount time) > > Ceratinly all of these things are optional (as you can see above you > have to select it from kernel config). The JFFS2 image produced by > sumtool is also usable with previous kernel because the summary node is > JFFS2_FEATURE_RWCOMPAT_DELETE. > > I think it can be usefull not only for us. David, may I commit it to the > CVS? > > Regards, > Ferenc -- Best Regards, Artem B. Bityuckiy, St.-Petersburg, Russia.