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Politics : Formerly About Advanced Micro Devices -- Ignore unavailable to you. Want to Upgrade?


To: Petz who wrote (62331)6/18/1999 4:32:00 PM
From: Elmer  Read Replies (3) | Respond to of 1572154
 
K7 vrs Xeon SPEC scores.

Intel SpecInt95 scores are actually SPECint_base95 scores and the highest reported score is 24.4, not 24.3 so using the K7 SPECint_base95 score of 25.1 you would get:

25.1/24.4 = 102.86% or a 2.86% improvement, not +5.76 as claimed.

I won't attempt to close the gap on floating point as it is clear there is no point.

EP



To: Petz who wrote (62331)6/20/1999 11:20:00 PM
From: Tenchusatsu  Read Replies (3) | Respond to of 1572154
 
Petz and all, re: AMD's point-to-point bus and multiprocessor performance,

After doing a little research into the subject, I learned a little something interesting about the K7's point-to-point bus. In multiprocessor systems, compared to a shared processor bus like Xeon, the K7 actually has longer latency, even though data bandwidth is greater. The reason has to do with cache coherence. I'll avoid the gory details, but suffice to say that with a shared multiprocessor bus, every processor can watch the transactions go by on the bus and snoop accordingly. With point-to-point connections, if a processor issues a memory access, all the other processors must be notified separately before the memory access can go through.

That's one advantage of a shared multiprocessor bus. So for two-to-four-way systems, Xeon will exhibit lower latencies than K7. On the other hand, for eight way systems and higher, the latency advantage will probably disappear because the Xeon will have to resort to multiple buses which need to "snoop" each other, thereby adding latency.

It'll be interesting to see how well multiprocessor K7 servers run on server benchmarks like TPC, especially with the point-to-point connections that isn't the panacea that AMD makes it out to be.

Tenchusatsu