This is still a winner if we actually use fewer indirect blocks
in the search.
My estimate is that a btree/extents based structure will pay for itself
only if the average extent for large files is more than 12 blocks.
I assume 3 words/extent on the leaf nodes. 2 words in internal nodes
and btree nodes 50% full on the average.
Small files can hold 5 extents right in the inode.
> And, why do we have to store
> both logical and physical blocks, is there any nontrivial translation
> between them?
The "logical" block is the file block number.
The "physical" block is the device block number.
Without both fields it is impossible to do a binary search
(just a linear search through the whole file) and also it is impossible
to have sparse files.
Itai
-- Itai Nahshon nahshon@actcom.co.il Also nahshon@vnet.ibm.com- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu