On Wed, 19 May 1999, Michael McCormack wrote:
> Hey Jan,
>
> i'll help you finish it and create a new release, but i haven't got the time
> for around two weeks, as i'm moving :-(
>
> Has anybody heard of wrapfs? Does anybody think that it would be a good idea
> to make userfs into a stackable filesystem module?
Hi Michael,
I did. I've searched through internet quite a long time while I
hesitated, how should I write a fs in user-space... ;-)
Erez Zadok from Columbia University NY is (I think) the main author. The
idea of the stackable filesystem and his wrapfs was to create a layer
between VFS and other _native_ filesystems, which would (among other
things) simplified the API for fs programmers.
One of the main disadvantages of user-level filesystems is their poor
performance due to high context switchings. Though the overhead of wrapfs
is not very high (it should 5-10%), it is next performance change for the
worse.
I think the best alternative could be good 'userfs' with features of
kernel 2.2.x support, glibc/libc, SMP, ... etc. which would be stable and
_fast_ as much as possible. The simplified or more abstract API for
user-level fs programmers could be done by changing the protocol...
Jim
.~. Jan Jirmásek
/V\ jimik(at)lucy.troja.mff.cuni.cz, http://mujweb.cz/www/jirmasek
// \
/( )\ Linux, the choice of a GNU generation.
^^-^^
