Messages in this thread | | | Date | Fri, 9 Jan 1998 20:13:45 -0500 | From | "Theodore Y. Ts'o" <> | Subject | Re: EXT2 and contiguous files |
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Matti,
You should talk to Stephen Tweedie about this. I've talked to him on this subject, and he's had plans to do something very much like this. One of his ideas was that even without making a file format change, you could have an in-memory cache which stored the block locations of the inode in terms of block-runs. This would allow the ext2 filesystem to access files without needing to mess with the indirect blocks, and you'd get a performance win even without changing the on-disk format.
Of course, for the ultimate in performance gain, you would have to change the on-disk format, and the way to do this compatibly would be to use an ext2 inode flag to designate whether an inode is using the old format or the new format. As you noted, for sparse files, for obvious reasons the old format is superior.
In fact, for a first-cut implementation, it might make sense to make a kernel which only creates files in the new format assuming that the entries all fit in i_blocks, and immediately converts things to the old format once that assumption is violated.
- Ted
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