Hello Paul, it has been a while, but this is what I remember from JFFS2: - on writing data, at minimum 128B is always written (is a configuration option, check ecos.ecc) in a node, and the maximum is 4kB (also a configuration option) before a new node is started - such a node needs meta-data; when using dynamic allocation, each node will consume 24B; when using the static allocation option it only consumes the needed 16B - Per file there is also file meta-data, 64B I think. - be careful with writing a file in small chunks: for each write a node is created. When opening the file again, each node consumes 100B of RAM; so opening a 1000B file written in 100 times 10B, will consume 100*100B of RAM! And this also thrashes your file system - and when your file system is full, a garbage collect will be done, and that can easily time-out a TFTP-write. - JFFS2 needs a lot of RAM, for example for a 60MB partition, you really need 1MB of RAM for JFFS2 only, even better 2MB. - if JFFS2 will run on a system that will normally be never powered-down, and if you use JFFS2 to write to, you need to do some garbage collect from time to time, but garbage collect is not thread-safe..
Success, Jürgen > -----Original Message----- > From: ecos-discuss-ow...@ecos.sourceware.org [mailto:ecos-discuss- > ow...@ecos.sourceware.org] On Behalf Of Paul MAILLET > Sent: dinsdag 31 mei 2011 17:04 > To: ecos-discuss@ecos.sourceware.org > Subject: [ECOS] Re: RE : JFFS2 for NAND flash file system > > Hi, > > I have been able to configure and run JFFS2 on my target, I have > successfully tested basics functionalities. As my target use NAND > flash and JFFS2 doesn't support it, I would like to know if it is > really problematic or dangerous or anything that I should be aware of > when using it on NAND flash device. > > Also I have looked for information about block usage like how many > blocks are used when I create a directory or an empty file but I did > not find these data. > > Can someone shed some ligth on this? > > Thanks, > Best regards, > Paul > > -- > Before posting, please read the FAQ: > http://ecos.sourceware.org/fom/ecos > and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
