The problem with cfs is that you still suffer the RPC to check for validity.
With 100ms of RTT, count 5 and you have a second. Also, for synthesized
files,
the cache does not save you from doing a walk, open, read.
I'll be accused of being a heretic, but let me claim that much of the
design of IMAP is geared towards avoiding those RTTs for that very reason.
A good IMAP client wins by doing intelligent cacheing, and it gets there
by using the subtle aspects of the protocol that accomodate that.
Much as people slag the protocol, it does work well over slow (high
latency) links, given a client that understands the protocol (sadly, most
don't).
I'm very curious about the efficiency of cfs, but my P9 environment
doesn't have a remote terminal. It would be interesting to instrument cfs
and collect some stats on the protocol behaviour behind the cache ...
--lyndon
