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Topic Title: AMD Dual-Core CPU vs Two Single Core AMD CPUs
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Created On: 11/29/2005 05:22 PM
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 11/29/2005 05:22 PM
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pjtodd
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Posts: 2
Joined: 11/29/2005

Is anyone aware of a Memory-Bandwidth Test between a single AMD Dual-Core CPU vs Two Single-Core CPU's running at the same clock speed?
 11/29/2005 08:40 PM
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Bitey
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Seen quite a few.

but to summarise

The dual cpu is nearly twice that of the dual core minus a bit for the overhead of using registered memory and higher latencies.

This "doubling" will only occur if the benchmark uses at least 2 threads, eg both CPU's get used.

You also need a NUMA capable board to ensure that each CPU uses its local memory in preference to the other CPU's memory.

If you search around the opteron forums you will see a few benchmarks, but if you want I can run some on my dual CPU system and hopefully someone can run some comparable ones on a dual core system.

PS if you install sisoft sandra you will have a bunch of stock benchmarks from standard systems that you look at.
 11/30/2005 09:09 AM
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pjtodd
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Joined: 11/29/2005

Thank you.

QUOTE(Bitey @ Nov 29 2005, 08:40 PM)Seen quite a few.

but to summarise

The dual cpu is nearly twice that of the dual core minus a bit for the overhead of using registered memory and higher latencies.

This "doubling" will only occur if the benchmark uses at least 2 threads, eg both CPU's get used.

You also need a NUMA capable board to ensure that each CPU uses its local memory in preference to the other CPU's memory.

If you search around the opteron forums you will see a few benchmarks, but if you want I can run some on my dual CPU system and hopefully someone can run some comparable ones on a dual core system.

PS if you install sisoft sandra you will have a bunch of stock benchmarks from standard systems that you look at.
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 11/30/2005 01:01 PM
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mckennma
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Posts: 2989
Joined: 06/01/2005

You want E4 or E6 Stepping on the new CPU for best memory support. I upgrade from dual 240 CG stepping to dual 265 E6 stepping. I also turned on NUMA support.

(Sandra Pro 2005)
Dual 240s
11.000 MIPS
without NUMA: 3.4 GHz memory bandwidth
with NUMA: 5.8 GHz memory bandwidth

Dual 265s
35,800 MIPS
with NUMA: 8.5 GHz memory bandwidth




-------------------------
Tyan Thunder K8WE
Dual AMD 280 Opterons
8GB NUMA enabled DDR333 2.5-3-3-7 RAM
PCI-X SCSI RAID
http://69.14.190.80
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