[Beowulf] Q: IB message rate & large core counts (per node)?

Scott Atchley atchley at myri.com
Wed Feb 24 21:49:38 EST 2010

On Feb 23, 2010, at 6:16 PM, Brice Goglin wrote:

> Greg Lindahl wrote:
>>> now that I'm inventorying ignorance, I don't really understand why RDMA 
>>> always seems to be presented as a big hardware issue.  wouldn't it be 
>>> pretty easy to define an eth or IP-level protocol to do remote puts,
>>> gets, even test-and-set or reduce primitives, where the interrupt handler
>>> could twiddle registered blobs of user memory on the target side?
>> That approach is called Active Messages, and can be bolted on to
>> pretty much every messaging implementation. Doesn't OpenMX provide
>> that kind of interface?
> Open-MX offers what MX offers: no explicit RDMA interface, only 2-sided.
> But something similar to a remote get is used internally for large
> messages. It wouldn't be hard to mplement some RDMA-like features in
> such a software-only model like Mark said above.
> Brice

Don't forget the unexpected handler which can provide some Active Message behavior.

Beowulf mailing list, Beowulf at beowulf.org sponsored by Penguin Computing
To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf

More information about the Beowulf mailing list