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 1CCLat-0001GQ-2s for linux-mtd@lists.infradead.org; Tue, 28 Sep 2004 13:16:56 -0400 Message-ID: <41599C42.4030507@yandex.ru> Date: Tue, 28 Sep 2004 21:15:46 +0400 From: "Artem B. Bityuckiy" MIME-Version: 1.0 To: David Woodhouse References: <41595913.4040007@yandex.ru> <1096375038.30942.30.camel@hades.cambridge.redhat.com> <41596471.5020108@yandex.ru> <1096377761.30942.58.camel@hades.cambridge.redhat.com> <41596913.6080207@yandex.ru> <1096379132.30942.66.camel@hades.cambridge.redhat.com> <41596DDC.3000506@yandex.ru> <1096380254.30942.77.camel@hades.cambridge.redhat.com> <1096381863.17956.12.camel@weaponx.rchland.ibm.com> <41597985.3080803@yandex.ru> <1096383492.30942.83.camel@hades.cambridge.redhat.com> <415995EC.8010004@yandex.ru> <1096390699.30942.110.camel@hades.cambridge.redhat.com> In-Reply-To: <1096390699.30942.110.camel@hades.cambridge.redhat.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-mtd@lists.infradead.org Subject: Re: JFFS2 an nodes checking List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , David Woodhouse wrote: > Yeah, but we _know_ we're going to write to the flash when we write to > regular files. That's not necessarily intuitively true for FIFOs. You > expect your data to get to the other end of the FIFO... you don't > necessarily expect anything to be written to the flash. > Josh Boyer wrote: > Fifos don't really hold data, they are just named pipes. When you write > to it, it's mostly handled by the VFS. The actual data isn't written > out by JFFS2. Except that we have to update st_ctime and st_mtime, > which causes more nodes. Yes.. I thought in contents of the optimization I spoke about and tried to understand this problem in that context. I spoke about iget() delay. But the FIFO issue is another. Ok, thanks for reply! David Woodhouse wrote: > On NOR we can scribble over the old nodes with the old mtime/ctime. On > NAND we can't so we end up with lots of nodes which are _potentially_ > valid and which all have to be compared. Josh Boyer wrote: > Because you can't directly obsolete a node on NAND flash (and some weird > versions of NOR flash as well). So obsolete nodes are actually written > out to flash instead of just flipping a bit in the existing node. Yes, I must have guess this myself. :-) -- Best Regards, Artem B. Bityuckiy, St.-Petersburg, Russia.