[PATCH] IFS: Inode FileSystem

[Suleiman Souhlal]

Hi,

On Jun 6, 2005, at 12:53 AM, Scott Long wrote:

> Maxim Sobolev wrote:
>
>> Are there any real users of this FS? If my memory serves,
>> Adrian's plan was to add IFS support into the squid. I
>> wonder if it had happened and whether or not it actually
>> provides any real performance benefit.
>> -Maxim
>>
>
> IFS is centered around the observation that most apps already keep a
> metamapping of 'filename ABC = data XYZ', where the filename is really
> nothing more than a unique identifier for the data.  Expressive
> filenames and file hierachies are useful for humans, but matter
> little to computers.  The name "squid/cache/a/b/abc" has as much
> meaning to a computer as the name "12345" (which might be the inode
> number of the file).  So taking this into account, you can strip
> out all the overhead of recursive namei lookups, directory data reads,
> directory hashing, etc, and just use the inode number directly as the
> identifier for inodes.  Looking up by inode is a O(1) operation
> consisting of merely using the number to index into a inode array in a
> particular cylinder group.  It's a huge win for CPU overhead in the
> filesystem, especially when we start talking about increasing the size
> of m_links field and possibly going to 64-bit inode numbers.

Talking about going to 64-bit inode numbers, how would we deal with  
the change in stat(2)?

--
Suleiman Souhlal     | ssouhlal at vt.edu
The FreeBSD Project  | ssouhlal at FreeBSD.org