Re: [rfc] Near-constant time directory index for Ext2

From: Ed Tomlinson (
Date: Tue Feb 20 2001 - 21:35:15 EST

Alan Cox wrote:

>> probably a bad idea to use it, because in theory at least the VFS layer
>> might decide to switch the hash function around. I'm more interested in
>> hearing whether it's a good hash, and maybe we could improve the VFS hash
>> enough that there's no reason to use anything else..
> Reiserfs seems to have done a lot of work on this and be using tea, which is
> also nice as tea is non trivial to abuse as a user to create pessimal file
> searches intentionally

The default in reiserfs is now the R5 hash, but you are right that lots of efforts went
into finding this hash. This includes testing various hashes on real directory
structures to see which one worked best. R5 won.

Ed Tomlinson
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This archive was generated by hypermail 2b29 : Fri Feb 23 2001 - 21:00:24 EST