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shinoj83
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More about processors and their cores

Hello all,

I like to know more about

What is the difference between SMP and VSMP ?

What is VCPU ?

What is Logical CPU ?

What is the difference between Virtual CPU and Logical CPU

What does 4way and 8way Vsmp support means ?

I did find almost few answers for my above questions but neither it was very clear nor i understood the basic concept.

Also, what is maximum number of cores available in the market ?

Can any one please shed some light on my above queries please

Thanks in advance guys!!!!!!

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GaneshNetworks
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What is the difference between SMP and VSMP ?
SMP - involves a multiprocessor computer hardware architecture where two or more identical processors are connected to a single shared main memory and are controlled by a single OS instance.
VSMP - VMware Virtual SMP is a utility that allows a single virtual machine to use two or more processors simultaneously.

What is VCPU ?
Nothing but a virtual CPU. For more - http://communities.vmware.com/message/1237724

What is Logical CPU ?
There is no difference between VCPU and Logical CPU, both are same.

What is the difference between Virtual CPU and Logical CPU?
NIL

What does 4way and 8way Vsmp support means ?
4way - Allows a single virtual machine to use up to 4 virtual CPUs at a time (this was previously 4 vCPUs in VI3)
8way - Allows a single virtual machine to use up to 8 virtual CPUs at a time


what is maximum number of cores available in the market ?

12-core AMD Opteron is code-named “Magny-Cours”
12-core INTEL i7-980 is code-named "GulfTown"

~GaneshNetworks™~ If you found this or other information useful, please consider awarding points for "Correct" or "Helpful".

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GaneshNetworks
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What is the difference between SMP and VSMP ?
SMP - involves a multiprocessor computer hardware architecture where two or more identical processors are connected to a single shared main memory and are controlled by a single OS instance.
VSMP - VMware Virtual SMP is a utility that allows a single virtual machine to use two or more processors simultaneously.

What is VCPU ?
Nothing but a virtual CPU. For more - http://communities.vmware.com/message/1237724

What is Logical CPU ?
There is no difference between VCPU and Logical CPU, both are same.

What is the difference between Virtual CPU and Logical CPU?
NIL

What does 4way and 8way Vsmp support means ?
4way - Allows a single virtual machine to use up to 4 virtual CPUs at a time (this was previously 4 vCPUs in VI3)
8way - Allows a single virtual machine to use up to 8 virtual CPUs at a time


what is maximum number of cores available in the market ?

12-core AMD Opteron is code-named “Magny-Cours”
12-core INTEL i7-980 is code-named "GulfTown"

~GaneshNetworks™~ If you found this or other information useful, please consider awarding points for "Correct" or "Helpful".
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shinoj83
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Hi Guys,

Thank you very much for the explanation. Can i also ask one more question please

If i have 2 quad core physical processor, how many VM's can i deploy provided each VM should have 2 cpu's

Please reply with an example

Regards

Shinoj

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GaneshNetworks
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It depends upon the usage of your VMs.

eg.,

If you give 2 cores (2x2.4Ghz) to your VM1, that 2 cores won't be reserved to VM1. But 2 cores are the maximum of VM1. Take a look at the below snippet:

Maximums.JPG

Thanks,

Ganesh

~GaneshNetworks™~ If you found this or other information useful, please consider awarding points for "Correct" or "Helpful".
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shinoj83
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Hi Ganesh,

Sorry, I think i did put my question in right way.

I intend to ask If my server is configured with 2 quad core processor then

1) How many number of VM's can be configured in my server ensuring all VM's i create should have 2 Cpu's.

===============================================================================

From the below Maximum's from Vmware ESX

Number of Virtual CPU's per host    - 256  

Number of cores per host - 64

Number of Logical CPU's

(Hyperthreading enabled)  - 64

Number of Virtual CPU's per core

a)  How do relate the above numbers to physical processor

b) If my understanding is correct, If i have 2 quad core processor then i will end up having 8 VCPU's, in that case how many VM's can be configured provided all VM's should have 2 CPU's

***** Sorry i am unable to  see the Picture you  uploaded****

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prakashraj
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No of VM deployments depends on CPU,RAM and storage resources availability on the HOST

Please check the below link for better CPU understanding

http://www.boche.net/blog/index.php/2010/07/25/vsphere-4-1-multicore-virtual-cpus/

Prakash

Message was edited by: prakashraj

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weinstein5
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Welcome to the Forums - just to clarify a Logical CPU is reference to the logical locations a physical CPU can schedule a thread of execution - this can be a physical or a hyper thread. For example your dual quad core cpu are two physical presenting 8 cores - these 8 cores are called Logical CPUs. If the processors is capable of hypertheading then when it is enabled you will have 16 Logical CPUs -

In terms of the number of VMs you can run 6-8 single vCPUs per core assuming you have sufficient sufficient resources including memory, network and disk bandwidth.

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shinoj83
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Thank you very much!

I am sorry to duplicate the questions, I am little bit confused please help me out with this

From your below statement when you said 16 logical Vcpu's does that mean i can configure only 8 VM's with 2 processor each ?

what does vsmp - 4way and 8 way means

Also i read a vmware forum where it was mentioned that hyperthreading is not available in the current processors. Does that bring down the available number of logical processors ?

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weinstein5
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You can oversommit the number ofprocessors because the vmkenel can schedule the virtual processors to run when need - considering VMs with a single vCPU - you can host 6-8 vCPU per LCPU so you dual quad CPU machine you could handle 48 virtual single vCPU machines as long as you have sufficient memory. It is my experience you will force memory or disk contention before you run out of CPU capacity

vSMP means how many virtual CPUs you can assign to a VM - 4 way vsmp is 4 vCPUs and 8 way is 8 virtual CPUs - you will need the enterprise plus license to be able assign more than 4 vCPUs to a VM - also please not best practice is to always start with a single vCPU because you can always add additional vCPUs -

Yes if hyperthreading is not available (or it is disabled) for your processors than you will only have 8 LCPUs instead of 16

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shinoj83
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Sorry for the delayed response it just answers my question. Awesome!!!! Thank you very much.Smiley Happy

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Pompies
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Everytime I read up on this I get more confused,

If I have 2 x 4 core E5420 and vSphere Enterprise and 2008 R2 VM, I create a 8 vCPU VM.

Would I get better performance than if I had a 2vCPU VM, as I am over committing “actual CPU’s” and will the scheduler cause a performance hit due to overhead to allocate instructions to the 8 vCPU’s?

Note, I configured the 8vCPU with cpuid.coresPerSocket 4 can someone please confirm that there is no performance gain for this setting other that the way the CPUS are presented within the OS?

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