Sigh. For the ultimate performance gain, for small files
(with size less than some threshold), surely it is best to store the
data of the file directly in the inode. In some ways, this parallels
the decision on whether to store a symbolic link in the inode or in a
separate data block.
I've looked at this, too. There is space in i_blocks to store 60 bytes
of data. The number of files on a typical linux filesystem which is
small enough to fit under that threshold is very small, and so I judged
that it wouldn't be worth the implementation complexity to implement it.
It was clearly worth it for symbolic links, but it doesn't appear to be
worth it for files.
You could in theory up the size of the inode, to make more room for
storing small files in the inode. For example, you could double it from
128 bytes to 256 bytes, so you could now store up to 188 bytes. But now
you've doubled the overhead of the inode table, and it means that a
single disk block contains half as many inode blocks.
- Ted