Many small files instead of one large files - writing, wearing, mount-time?

Martin Egholm Nielsen martin at
Wed Mar 9 06:11:06 EST 2005

>>Hence, me initial strategy was to have a file in NAND for each resource. 
>>However, I noticed that mount-time increased "severely" when many files 
>>were put on the device, and doing an "ls" first time on the 
>>device/directory took lots of time as well.
> Owing to its design JFFS2 works extremely slowly wit directories
> containing so many files.
 From IRC - just to keep the ML thread up to date:

egholm:   But could I make it faster by putting them into sub-directories?

dedekind: you could if the number of your subdirectories is small

dedekind: besically, JFFS2 uses the list to keep all the directory's 

dedekind: so, the performance is linear dependend on the number of children

egholm:   number of childrens - in one layer only? or accumulated children?

dedekind: in one layer

egholm:   super! Then that may be a solution! Thanx

// Martin

>>Unfortunately low mount-time is one of the factors giving the user a 
>>good experience with the system, so I started considering another 
>>strategy - namely one large file to hold all these states.
>>However, I'm a bit concerned how fopen( ..., "rw" ) is handled 
>>underneith when I flush/sync the filedescriptor if I only mess with a 
>>small part of the file. Is the entire file flushed to NAND once more, or 
>>does Linux+JFFS2 handle this, and only write the parts (inodes) that are 
> Don't worry, Only that "messed" peace will be flushed. The "large file"
> solution will be definitely faster.

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