[CentOS] cachefs efficiency

[Grant Street]

Hi

We are testing out the efficiency of cachefs and I was wondering what
values other people use to decide if
* cachefs is providing value?
* cache size is the right/best/optimal size?
* There is enough cache hits to make it worth while?
* what files are being re-used(read from cache) the most?
* how do I know if file are being opened with directIO ?

I have access to
   /proc/fs/fscache/stats
and
   /proc/fs/fscache/objects

But the documentation is not clear in fscache.txt

Thanks in advance.

Grant