[Pkg-ofed-devel] Setting mtu to 4k does not work

Guy Coates gmpc at sanger.ac.uk
Wed Oct 14 12:59:14 UTC 2009

> Any idea on how to resolve this issue? 

Hi Simon,

Google thinks that you need to configure your subnet manager to allow MTU > 2048.

Good starting points will be:



and the opensm man page.

As far as I can tell, opensm does not ship with any example configuration files, 
so I don't know the exact options you need to give opensm.

If you do find some, let me know and I will add them to the future package releases.

Ipoib MTU size is discussed in:


>Is it even worth it?

No idea, I'm afraid. The linux IB mailing list might be able to help you, as 
well as answering any opensm config questions.

linux-rdma-owner at vger.kernel.org


Dr. Guy Coates,  Informatics System Group
The Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1HH, UK
Tel: +44 (0)1223 834244 x 6925
Fax: +44 (0)1223 496802

 The Wellcome Trust Sanger Institute is operated by Genome Research 
 Limited, a charity registered in England with number 1021457 and a 
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