[mvapich-discuss] MTU size on homogenous mlx4 QDR systems

[Christian Guggenberger]

On Mon, Dec 14, 2009 at 07:42:40PM +0100, Peter Kjellstrom wrote:
> On Friday 11 December 2009, Bernd Kallies wrote:
> > We use "old" MT25208 InfiniHost III and MT26418 ConnectX (4x DDR per
> > port, 2 ports per host) with 64k MTUs, as shipped by our vendor.
> 
> You're confused, the OP likely refered to the IB MTU (not ethernet like IPoIB 
> MTU used with the tcp/ip stack). 
> 
yep. I was reffering to the "hardware" MTU (or however one would call it). It usually
defaults to 2K on most hardware (with quirks to set it down to 1K on tavour-based
devices, IIRC). mlx4-based adapters offer 4K MTUs with a special module parameter.
I am just not sure if it makes sense to enable them ...

cheers.
 - Christian