cyrus-dir-hash?

[Gary Mills]

On Fri, Nov 01, 2002 at 01:24:56PM +0800, Liu Jinhui wrote:
>     When I compile cyrus-2.0.16, I used a patch called cyrus-dir-hash from http://mail.cc.umanitoba.ca/source/

This patch is included with recent version of Cyrus.  Only a configure
option is required to activate it.

> It simply centralizes all directory hashing into one function: dir_hash_c(). By default, 
> this function uses the old hashing scheme, based on the first letter of the user name. 
> When the compile-time symbol USE_DIR_FULL is defined, it uses the new scheme that hashes 
> all letters of the user name to provide an even hash distribution. 
>     I wonder how much it will help the performance of cryrus-imap.
>     In my situation , almost all users name are beginning with the same letter: 'u'.

The performance improvement depends on how many users you have, and on
how well your UFS implimentation handles large directories.  With Solaris,
for example, performance is pretty bad with 20,000 entries in one directory.
It's reasonable with only 1000 entries.

-- 
-Gary Mills-    -Unix Support-    -U of M Academic Computing and Networking-