Re: [PATCH] cifs: lower default wsize when unix extensions are not used

["Björn JACKE" <bj-PS7XAnAlDA+VvDNblw4Uiw@public.gmane.org>]

On 2011-11-09 at 16:04 -0500 Jeff Layton sent off:
> On Wed, 9 Nov 2011 14:55:36 -0600
> Steve French <smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> 
> > How much of a performance hit does this make?  I would expect that
> > dropping the writesize by more than 50% to most non-Samba servers to
> > work around a bug in Solaris seems extreme.  If this hurts our
> > performance measurably, it may be more pragmatic to limit the wsize
> > change to a subset of these (e.g. based on server type) - seems more
> > fair to not punish other servers for a Solaris bug.
> > 
> 
> I'm not sure how big a hit it will be, but it won't be 0. As always, it
> depends on workload. The problem is, I'm not sure we can reliably
> detect when the server can't handle larger writes like this.

I've seen a performance drop from 60MB/s to 50MB/s on a 1GB switched network
when unix extensions were disabled just because the rsize was limited from 128k
to 64k. That was tested with Darwin's smbfs but the dropdown in performance of
cifs vfs will be similar. If this can be seen as a server bug I'd also like to
see Oracle fix their server and keep cifs vfs be able to use 128k.

Björn