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

[Michael S. Tsirkin]

Quoting r. Hal Rosenstock <halr at voltaire.com>:
> Subject: Re: [openib-general] [PATCH for-2.6.18] IB/cma: option to limitMTU to 1K
> 
> On Wed, 2006-09-13 at 11:57, Michael S. Tsirkin wrote:
> > Tavor systems get better performance with 1K MTU. Since there does
> > not seem to be any way to find out whether the remote system uses Tavor,
> > add an option to limit the MTU globally.
> 
> Can't Tavor be determined locally ?

It can, but we need this for remote tavor as well, anyway.

> And couldn't the remote end negotiate the MTU down (if Tavor) as well ?

The way to do this is would be for SA to select 1K MTU if it detects Tavor on one side
and if this does not conflict with MTU selector.

However
1. Even opensm does not implement this optimization yet
2. We need to work with existing SMs too

-- 
MST