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Hyperthreading on a ProLiant DL740

 
Hindy
Occasional Visitor

Hyperthreading on a ProLiant DL740

Hi,

I have several DL740 servers, fully loaded with 8 x Xeon MP (@2.5ghz). I'm running Windows Server 2003 Enterprise Edition.

My question is: how many CPU's should I see in device manager and task manager? I would expect the answer to be 16 (as I see 8 on my DL540 4 cpu servers). However, I only see 8.

Any ideas, much appreciated.
1 REPLY
ernst limbrunner
Trusted Contributor

Re: Hyperthreading on a ProLiant DL740

hi

maybe hyperthreading has been disabled in rbsu
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after post press F9 for setup (rbsu - rom based setup utility) - select advanced features - select hyperthreading
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that should do the job
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but be aware - hyperthraeding gives you between 20-30% for a single cpu, 2-15% for a dual processor system ..... so maybe you even LOOSE performance when you enable hyperthreading (OS overhead eats up the benefit)in an 8 proc-system
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the dl740 and dl760 have 4 cpus per frontside bus. with 8 logical cpus per bus you will run into bus saturation and this may have a negative effect
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the gain/loss depends on the software mix - so with 8 cpus you simply have to try.
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the bus loads also increases because when ht is enabled the cache size of each logical cpu is half the physical cache size - thus reducing cache hits - thus increasing bus loading
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best regards
ernesto