Eugen Leitl wrote:
On Tue, May 23, 2006 at 08:49:08AM -0500, Richard Walsh wrote:
Speaking of Hyper Transport 3.0 and its AC chassis-to-chassis
capabilities and 10 to 20
Gbps performance maximums one-way (non-coherent, off chassis I
believe), what do the
people that know say about scalability. Are we looking at coherency
I don't know (like it would stop me), but there are few-port HT switches,
and if there are several ports on one chassis one could wire up
some topology, which, hopefully, will match the problem.
HT switches ... ?? ... can you point me to a reference?
within the board complex
and basic reference ability off board or something else?
I'm not sure how this is different from vanilla packet-switched
MPI network. It's not about maintaining memory coherency.
Well, of course you can run MPI over it as you can on the Cray and
Altix, but
you are artificially separating memory in software that is in fact
closer in hardware.
That is where the pGAS programming models become more efficient. Remote
memory references expressed in the syntax and compiled to
instructions for
direct puts and gets without management or translation by a NIC. It
would seem
that HT 3.0 supports this model across chassis as long as the
programmer manages
memory synchronization.
Sounds like the Cray X1E pGAS memory model. Is there a role for
I don't think there is any other model but message passing. It's not
like this is a ccHT a la HORUS http://en.wikipedia.org/wiki/HORUS_interconnect
The inter-chassis, but non-coherent interface that HT 3.0 supports
would seem to work
very nicely with UPC and CAF. They run very well on the Cray X1,
which provides
coherent memory on-board only as well.
Regards,
rbw
------------------------------------------------------------------------
_______________________________________________
Beowulf mailing list, [email protected]
To change your subscription (digest mode or unsubscribe) visit
http://www.beowulf.org/mailman/listinfo/beowulf
--
Richard B. Walsh
Project Manager
Network Computing Services, Inc.
Army High Performance Computing Research Center (AHPCRC)
[EMAIL PROTECTED] | 612.337.3467
-----------------------------------------------------------------------
This message (including any attachments) may contain proprietary or
privileged information, the use and disclosure of which is legally
restricted. If you have received this message in error please notify
the sender by reply message, do not otherwise distribute it, and delete
this message, with all of its contents, from your files.
-----------------------------------------------------------------------
_______________________________________________
Beowulf mailing list, [email protected]
To change your subscription (digest mode or unsubscribe) visit
http://www.beowulf.org/mailman/listinfo/beowulf
