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Technology Stocks : Advanced Micro Devices - Moderated (AMD) -- Ignore unavailable to you. Want to Upgrade?

To: Joe NYC who wrote (69566)	1/30/2002 6:17:14 PM
From: Tenchusatsu	Read Replies (4) \| Respond to of 275872

Joe, actually for a 4-way Hammer system, the latency is worse than you think. Each time a memory access is initiated, the other processors need to be probed. The access cannot be retired until all of the probes are resolved. AMD's foils show a ring topology for a 4-way system. This means two hops for a probe to get to the furthest processor, then two hops for the probe response. This leads to a total of four hops, which should be considered the typical latency of any memory access. It's curious why AMD would choose a ring topology instead of a mesh like IBM's POWER4. But then again, I believe 4-way and 8-way Hammer will be cancelled anyway. ;-) Tenchusatsu