Re: [NFS] Re: [PATCH] zerocopy NFS for 2.5.36

[Andrew Theurer]

> >      > Congestion avoidance mechanism of NFS clients might cause this
> >      > situation.  I think the congestion window size is not enough
> >      > for high end machines.  You can make the window be larger as a
> >      > test.
> >
> > The congestion avoidance window is supposed to adapt to the bandwidth
> > that is available. Turn congestion avoidance off if you like, but my
> > experience is that doing so tends to seriously degrade performance as
> > the number of timeouts + resends skyrockets.
>
> Yes, you must be right.
>
> But I guess Andrew may use a great machine so that the transfer rate
> has exeeded the maximum size of the congestion avoidance window.
> Can we determin preferable maximum window size dynamically?

Is this a concern on the client only?  I can run a test with just one client
and see if I can saturate the 100Mbit adapter.  If I can, would we need to
make any adjustments then?  FYI, at 115 MB/sec total throughput, that's only
2.875 MB/sec for each of the 40 clients.  For the TCP result of 181 MB/sec,
that's 4.525 MB/sec, IMO, both of which are comfortable throughputs for a
100Mbit client.

Andrew Theurer