*BSD News Article 91619


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From: Michael Hancock <michaelh@cet.co.jp>
Newsgroups: comp.unix.bsd.freebsd.misc,comp.unix.bsd.bsdi.misc,comp.sys.sgi.misc
Subject: Re: no such thing as a "general user community"
Date: Sun, 23 Mar 1997 09:55:32 +0900
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Matt Dillon wrote:
> 
> :>>     XFs's claim to fame is:
> :>>
> :>>     * hashed directory lookups, making namei() on large directories more
> :>>       efficient (but only on large directories).
> :>
> :>Are you talking about an on disk structure.  FBSD has a simple sequential
> :>on disk directory structure.  There is a hashed name cache so assuming
> :>locality of reference...
> 
>     Yes, of course I am talking about the on-disk structure.  Nobody builds
>     an O(N) cache for this sort of stuff.  The on-disk structure is extremely
>     important under load, when the namei() cache hit ratio falls below 90%.

I wonder if the X in XFS is for eXtendible hashing.  Keys are put into disk 
pages.  A page is split when a new key is about to be inserted and the page is 
full.

Regards,


Mike Hancock