[openib-general] Fw: openib-general Digest, Vol 30, Issue 135

[Bernard King-Smith]

> ----- Message from "Shirley Ma" <xma at us.ibm.com> on Fri, 15 Dec 2006
> 09:06:03 -0800 -----
> 
> To:
> 
> "Michael S. Tsirkin" <mst at mellanox.co.il>
> 
> cc:
> 
> openib-general at openib.org
> 
> Subject:
> 
> Re: [openib-general] [PATCHv2] IPoIB CM Experimental support
> 
> "Michael S. Tsirkin" <mst at mellanox.co.il> wrote on 12/14/2006 09:14:38 
PM:
> 
> > > Hi, Michael,
> > > 
> > > Tried this patch, it didn't work on ehca. I couldn't change the mode 
from
> > > datagram to connected from /sys/class.
> > 
> > It's wroking as designed in that respect.  ehca does not implement 
> > srq - without
> > srq, there is no way to prepost receive buffers for a resonable number 
of
> > connections without running out of memory.
> > 
> > So it is falling back on datagram mode.
> > Talk to ehca guys to implement srq and connected mode will be enabled.
> Don't remember SRQ is a MUST for UC mode. Does this patch support 
> devices with SRQ in RC mode?

I don't think the IB HCA Spec requires SRQ support for RC but is an 
optional feature. There are two adapters right now that don't support SRQ 
which means to use IPoIB-CM on them you should make the use of SRQ an 
option setting. I agree that if it is available it should be used for 
scaling issues probably if available automatically set. But I would like 
to see us at least support the current hardware that meets the current 
SPEC.

Bernie King-Smith 
IBM Corporation
Server Group
Cluster System Performance 
wombat2 at us.ibm.com    (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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