Jumbo frame support for BGE_ASICREV_BCM5714

[YongHyeon PYUN]

On Mon, Mar 14, 2011 at 09:40:36PM -0700, Vijay Singh wrote:
> > As you know, BCM5714, BCM5715 and BCM5780 use unique jumbo frame
> > scheme that is not compatible with other controllers. All other
> > Broadcom controllers have better jumbo frame scheme. These
> > controllers have one send ring, one standard receive producer ring
> > and one receive return ring. In order to receive jumbo frames on
> > these controllers you have to increase Rx buffer size to hold 9k
> > sized jumbo frame. Two Rx modes(standard Rx BDs and extended Rx
> > BDs) are supported for these controllers. Using extended Rx BDs on
> > BCM5714/BCM5715/BCM5780 reduces the number of Rx BDs to 256 entries
> > which shall reduce the performance. I would use standard Rx BDs to
> > hold 512 entries for RX buffers.
> >
> > I think I received jumbo frame support request for these
> > controllers in past. At that time I had no interests on
> > implementing it due to severe implementation differences. What is
> > your main reason to use jumbo frame on this controller? What is
> > your expectation on performance numbers? I guess no other OSes
> > support jumbo frame on this controller.
> 
> Hi Pyun, I am stuck with this NIC due to it being the one present in
> the HW platform that I have to support. The performance is expectation
> is mainly for apps that use large payloads (where something TSO would
> have helped).
> 

Here is experimental patch which I tried not to penalize other
controllers.  I don't have BCM5714 controllers so I don't know
whether it works or not. The patch was generated against HEAD and
it would be cleanly applied to 8.2R/7.4R. Due to large bge(4)
changes I guess it wouldn't be applied to 7.2R. But I guess you can
install 8.2R/7.4R to one of your box and experiment this patch for
a while then you can backport this to 7.2R.
You can find the patch at the following URL.
http://people.freebsd.org/~yongari/bge/bge.5714.jumbo.diff

> -vijay