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SubjectRe: [patch[ Simple Topology API

Chris Friesen wrote:

>> Beyond 8-way, you need glue logic (hypertransport switches?) and
>> latency seems bound to become an issue.

>Nope. Just extend the ladder. Each cpu talks to three other entities,
>either cpu or I/O. Can be extended arbitrarily until latencies are too
>high.

You seem to be missing one critical piece from the OLS talk. The HT
protocol (or something related) can't handle more than 8 CPU's in a single
configuration. You need to have some kind of bridge to connect
more than 8CPU's together, although systems with more than 8 CPU's have
not been discussed officially anywhere, afaik.

8 CPU's and less belongs to the SUMO category (Sufficiently Uniform Memory
Organization, apparently new AMD terminology) whereas 9 CPU's and more is
likely to be NUMA.

--
Jukka Honkela


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