Re: [PATCH 2/2] rdma/cm: allow user to specify IP to DGID mapping

Jason Gunthorpe
2009-10-07T21:45:59Z

On Wed, Oct 07, 2009 at 02:20:29PM -0700, Hefty, Sean wrote:
> >You are trying to make the smallest change possible to work around a
> >performance problem caused by ineffecient abstractions by completely
> >breaking the abstraction.
>
> The performance problem being addressed here is not caused by an
> inefficient abstraction. It's caused by having a single,
> centralized SM incapable of scaling to the cluster sizes that
> customers want to use.

The SM scaling is a side effect of the IP RDMA CM design. Since the IP
RDMA CM design and abstraction require the ARP and PR queries - it is
the root inefficiency - the SM scaling is the consequence. IB GID CM
does not have this mandatory behavior, you can get your PR data from
wherever you want.

Jason