----- Message from "Roland Dreier" <[EMAIL PROTECTED]> on Wed, 10 > Jan 2007 07:15:12 -0800 ----- > > To: > > "Michael S. Tsirkin" <[EMAIL PROTECTED]> > > cc: > > [email protected] > > Subject: > > Re: [openib-general] [PATCHv4] IPoIB CM Experimental support > > > - Using path MTU discovery, multicast and UDP traffic to UD mode now work, > > only a small number of packets is dropped. > > How does this work? What happens if I set my MTU to 8K and send a > 8000-byte UDP message to a node that doesn't implement CM? What > happens if I send an 8000-byte UDP multicast?
If we support a large interface MTU using RC, then I would expect both UDP and TCP to both use RC mode. It doesn't make sense for UDP to use UD mode because of the higher CPU overhead and lower bandwdith, when TCP uses RC. Can we not support UDP multicast over RC? > > I didn't think UDP did path MTU discovery by default... > > - R. > > > Bernie King-Smith IBM Corporation Server Group Cluster System Performance [EMAIL PROTECTED] (845)433-8483 Tie. 293-8483 or wombat2 on NOTES "We are not responsible for the world we are born into, only for the world we leave when we die. So we have to accept what has gone before us and work to change the only thing we can, -- The Future." William Shatner
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