[linux-cifs-client] Asynchronous readahead limit

[Steve French]

Although there are significant functional differences, ... it would be
useful as sort of a sanity check to get baseline numbers from a couple
of other copy methods to see if the cifs numbers are in the right
ballpark.

Can you do a quick comparison with ftp, scp and/or nfs from the same
machines?  In addition, copy of the same file from the same server via
smbclient.

If one of those is significantly faster than cifs->Samba we may want to
push even harder at getting cifs in the ballpark of those.  We may also
need to push harder to optimize Samba server if we see indications that
the bottleneck is the server.

Also remember for large number of simultaneous requests to up max_mux
(which is configured on the Linux client via an insmod parm - do modinfo
on cifs.ko to see its name, and on the server is configured via
smb.conf).  It is not clear what the optimal number of simultaneous
requests to be queued on the server - but the more there are the fancier
we can make the server algorithm be for dispatching reads/writes.  50 is
the default.

I am quite interested in the results of this work.