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Old 2006-11-12, 23:15   #1
ahmerali
 
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Default L2 cache unknown with new CPUs

On a lot of the newer machines I am using, especially Conroes, Prime95 is displaying L2 cache size: unknown under CPU properties. Clearly I'm not getting the benefit of these CPUs. Sometimes even the L1 cache is not detected properly. Any advice on settings for this?
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Old 2006-11-13, 00:17   #2
Prime95
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Look in undoc.txt for the local.ini setting that tells prime95 how much L2 cache is available.
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Old 2006-11-13, 04:12   #3
ahmerali
 
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Thanks, that works for the L2 cache I suppose, even though the display in Prime95 still shows "unknown"...anything for the L1 cache, or is that not so important?
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Old 2006-11-13, 04:38   #4
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L1 cache is irrelevant in FFT selection
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Old 2006-11-13, 15:50   #5
Cruelty
 
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The question is how to set L2 cache in Prime95 on multi-core CPUs with L2 cache shared among several CPUs? Should I set "CpuL2CacheSize" variable to 50% of the total amount of L2 cache, for each copy of Prime95?
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Old 2006-11-14, 01:20   #6
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I'd do 50%. It will likely choose the same FFT implementation for either size.
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Old 2006-11-29, 13:40   #7
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Default L2 cache & FSB speed

I have found that L2 cache and FSB speed add nothing to speeding up LL testing. My XP2800 Thoroughbred outperforms my XP3200 Barton. The Barton has a 400 Mhz FSB and the Thoroughbred has a 333 FSB. It seems to me that CPU clock speed and the various SSE instruction sets make the most difference.
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Old 2006-11-30, 08:34   #8
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L2 cache size has (or at least should have) an impact on the performance while running LL test - it all depends on the length of FFT used.
Add "FullBench=1" to your prime.ini file and check the results
BTW: according to this document (page 42+43) your XP2800 has slight (50MHz) speed advantage over XP3200

Last fiddled with by Cruelty on 2006-11-30 at 08:44
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Old 2006-12-09, 19:08   #9
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OK. I put it in there and I will let you know how it turns out. Thanks for the tip.
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