From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail1.danielind.com ([12.19.96.6]) by pentafluge.infradead.org with esmtp (Exim 3.22 #1 (Red Hat Linux)) id 16QxSr-00074B-00 for ; Wed, 16 Jan 2002 21:19:21 +0000 Message-ID: <3C45EE36.4477E99A@daniel.com> Date: Wed, 16 Jan 2002 15:18:46 -0600 From: Vipin Malik MIME-Version: 1.0 To: Herman Oosthuysen CC: Cam Mayor , linux MTD mailing list Subject: Re: open question on flash speed/app blocking References: <02011512182209.16722@kilauea.iders.ca> <000e01c19ec6$b2cd5980$0100007f@localdomain.wni.com.wirelessnetworksinc.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-mtd-admin@lists.infradead.org Errors-To: linux-mtd-admin@lists.infradead.org List-Help: List-Post: List-Subscribe: , List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: http://www.embeddedlinuxworks.com/articles/jffs_guide.html then http://www.embeddedlinuxworks.com/articles/db_project.html I've also done quite a bit of blocking time tests on JFFS2 (about 6-8 months ago). See the (JFFS) list archives for details and graphs etc. Vipin Herman Oosthuysen wrote: > Hmm, the problem is not writing to flash per se, but rather garbage > collection, which requires the erase of dirty Flash sectors. Erasing a > sector on an Intel chip can take from a couple hundred milliseconds to about > 15 seconds, depending on the age of the device - by the time a chip gets to > 15 seconds, I usually toss them away. Flash chips tend to get slower with > age. So, you have to repeat your tests a few hundred thousand times before > you can draw any real conclusions. This also means that the worst case > performance will be about the same, irrespective of the file system used, > since the hardware constraints will eventually dominate. > > If your system has to write to flash every few seconds, then consider using > a file system that has a large write cache, to enable you to survive the > periods when the system is busy erasing a sector. > -- > Herman Oosthuysen > Herman@WirelessNetworksInc.com > Suite 300, #3016, 5th Ave NE, > Calgary, Alberta, T2A 6K4, Canada > Phone: (403) 569-5688, Fax: (403) 235-3965 > ----- Original Message ----- > From: Cam Mayor > To: linux MTD mailing list > Sent: Tuesday, January 15, 2002 11:18 AM > Subject: open question on flash speed/app blocking > > Hi all, > > We're making an app that periodically writes a persistance file to flash. I > haven't actually gotten a flash file system area working yet on my board, so > i can't test this yet for speed. I know that the results will vary with > the > hardware, the filesystem used, and a handful of other factors. I'm assuming > that a write to the flash will be blocking - that is, nothing else will be > allowed to happen on the bus while that function is being performed. > > For a file the size of 32bytes, 1kByte, and 32kBtyes, what kind of blocking > delay might one expect from linux writing to flash for each of those file > sizes? What would be an optimum flash filesystem to use for something like > this? (if there is one) > > cheers, > cam > > ps. i'm using linux 2.4.6-rmk1-rayl1 and 2.4.16-rmk2. I could use the > latest > kernel, too, i just haven't gotten around to it. For development purposes, > i'm using a cirrus CDB89712 development board, which has the cs89712 > processor and some Intel 28f320B3 flash on it. > > ______________________________________________________ > Linux MTD discussion mailing list > http://lists.infradead.org/mailman/listinfo/linux-mtd/ > > ______________________________________________________ > Linux MTD discussion mailing list > http://lists.infradead.org/mailman/listinfo/linux-mtd/