Re: eCryptfs Design Document

[Miklos Szeredi]

> > > One dutifully wonders whether all this functionality could be
> > > provided via FUSE...
> > 
> > My main concern with FUSE has to do with shared memory mappings.
> 
> OK.  But I'm sure Miklos would appreciate help with that ;)

You bet.

> > My next concern is with regard to performance impact of constant
> > context switching during page reads and writes.
> 
> Maybe.  One could estimate the cost of that by benchmarking an existing
> (efficient) FUSE fs and then add fiddle factors.  If the number of copies
> is the same for in-kernel versus FUSE then one would expect the performance
> to be similar.  Especially if the encrypt/decryption cost perponderates.

The main overhead of FUSE is not in copies, but in context switching.
For I/O that can be mitigated by doing it in big chunks, otherwise the
only solution is adding more processors.

Miklos
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