[openib-general] [PATCH for-2.6.18] IB/cma: option to limitMTU to 1K

[Hal Rosenstock]

On Wed, 2006-09-13 at 15:05, Michael S. Tsirkin wrote:
> Quoting r. Hal Rosenstock <halr at voltaire.com>:
> > > If I understood Michael's comment properly, this will have the side
> > > effect that IPoIB won't work since IPoIB requires 2K MTUs.  As far as
> > > I know, there is no way to specify whether a path is needed for UD vs.
> > > RC in the path query.
> > 
> > I don't know how either. I don't think it can be done (at least
> > currently per the standard).
> 
> We don't really need to know whether path is for RC or UD QP.
> IPoIB needs MTU >= 2K so it should set mtu selector to >= 2K.

That's the default and not the minimum MTU (for IPoIB).

> In this case SM will return path with MTU >= 2K.
> CMA will not set mtu selector and then SM will choose MTU for best performance.