Re: Google Summer of Code Project: Port OpenAFS Client

[Antti Kantee <pooka%cs.hut.fi@localhost>]

On Wed Mar 31 2010 at 15:37:37 +0000, Christos Zoulas wrote:
> As for the performance of the server I think it depends on the workload
> (how many kernel-userland transitions you end up doing, and how agressive
> is your "attribute cache" to use NFS lingo).

While attribute caching in the file server does matter (network latency,
disk latency, what have you), I haven't stumbled across a workload where
lack of kernel attribute caching has any significant impact.  I'm not
saying an application scenario doesn't exist, just that I haven't run
into one.

ISTR Linux/FUSE implements kernel attribute caching and it's probably
trivial to add, but I haven't bothered doing it in NetBSD -- "when in
doubt, leave it out".

(ubc is different in this regard, mostly because of readahead support
and because it's easier to *not* have to tightrope with caching and
flushing gigabytes of data in several different caches.  after all,
there is only one set of main memory)