ygao
Contributor
Contributor

Hyperthreading

HI all:

We just recently purchased DL 380 G6 with the new nehelm CPU. We decided to enable hyperthreading. So we have 2 physical socket CPU with Quadcore, once the hyperthreading is enabled, the Logical processor is 16. Does that mean if we are using the 200% commiment rule, I have 16 CPUS to work with?

For example, if I have 8 CPUs, I can commite 16 CPUs to 8 VMs with 2 vCPU each. Now if I have 16, I can commit 32 CPUs to 16 vms with 2 vCPU each. Is that correct?

We are running vSphere and the VMs are Citrix Terminal servers.

Thanks in advance.

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4 Replies
RParker
Immortal
Immortal

I have 16 CPUS to work with?

NO. Physical cores. 2 Sockets with 4 CORE is 8 processors, not 16. So you have 8 1 vCPU VM's per core consolidation ratio.

And if I were you, I would turn hyperthreading OFF! It doesn't really buy you anything, the left over IO isn't enough to substantiate a VM, you will just end up with lop sided VM's in performance.

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ygao
Contributor
Contributor

Thanks for the info. We just heard conflcting reports, some says hyperthreading will help, some says no. Thanks.

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AWo
Immortal
Immortal

And if I were you, I would turn hyperthreading OFF! It doesn't really buy you anything, the left over IO isn't enough to substantiate a VM, you will just end up with lop sided VM's in performance.

Can you give some more details on that, please?


AWo

VCP / VMware vEXPERT 2009

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juststormY
Contributor
Contributor

And if I were you, I would turn hyperthreading OFF! It doesn't really buy you anything, the left over IO isn't enough to substantiate a VM, you will just end up with lop sided VM's in performance

Yes, it would be nice of you if you could explain this to us in detail!

Thanks a lot!

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