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Date: Mon, 15 Jul 2002 22:50:23 +0300 (EEST)
From: Jukka Honkela <fatal@ees2.oulu.fi>
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To: Chris Friesen <cfriesen@nortelnetworks.com>
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Subject: Re: [patch[ Simple Topology API
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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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