Re: [PATCH] New dcache / inode hash tuning patch

Ed Tomlinson (tomlins@cam.org)
Fri, 28 Feb 2003 23:31:31 -0500


Andi Kleen wrote:

> The hash function isn't good and the hash chains are far from evenly
> distributed. There are typically 30-40% empty buckets, while some
> others are rather long.
>
> In addition I think only a small fraction of the dentries are actually
> hot. (no numbers on that, sorry)

I wonder what would happen if you reordered the chains moving a 'found'
dentry to the front of the chain? If this could be done without
excessive locking it might help keep hot entries quickly accessable.
This operation should be cheaper given you are using hlists.

Ed Tomlinson

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