Logical processors question

[MyCroWave]

I have an intel S2600CP2 system board with 2 Intel E5-2620 processors.  I have hyperthreading enabled in the BIOS.  Since the processor is hyperthreaded, I would expect to see 24 logical processors (2 processors * 6 cores * 2 hyperthreaded = 24 Logcal procesors?) but when I look at my ESXi CPU configuration I only see 12 logical processors.  Is this right?  If not, does anyone have any thoughts on why it is only seeing 12 logical processors and what I need to do to correct this?

Thanks for any help.

[NathanosBlightc]

Enabling Hyper-Threading feature does not mean it will double count of existing physical cores on your server! HT causes each CPU cores logically act as a separate processor but it cannot increase number of your ESXi host logical processors

[sjesse]

That's not correct, logical processors are the number of cpu threads possible, so its sockets * core per socket * 2 if hyperthreading is indeed working. Just here is one example online

vCPU and logical CPU sizing with Hyper-Threading explained | VMwarebits.com

There is one host with 1 dual core cpu, that has 4 logical processors.

Here is an other post here explaining that

CPU per host, logical CPU per host and virtual CPU per core

That doesn't mean the logical processors all get the full use of the core, they share it.

There are other reasons why the number can be smaller.

[NathanosBlightc]

VMware mentioned here ​"a host that is enabled for hyperthreading should behave similarly to a host without hyperthreading". But however in another following link

said that "In hyperthreaded systems, each hardware thread is a logical processor. For example, a dual-core processor with hyperthreading enabled has two cores and four logical processors." Sorry for my mismatch about count of vCPU and logical proccessors. So as you said it must be enabled on both of BIOS settings and also host advanced settings: VMkernel.Boot.hyperthreading​ to work correctly

[MyCroWave]

Here is a screenshot of the VMkernel.Boot.hyperthreading setting and a photo of my bios setting. 

I don't know if this matters or not, I tried searching and couldn't find anything about this, I'm running the free version of esxi.  Would that cause this issue?

Thanks again for any help

[MyCroWave]

I figured it out thanks to the hint from sjesse​.

At some point in the past I must have overridden the HyperthreadingMitigation flag.  I noticed that as I was posting the prior message with the screen-shots.

I have reverted that flag back to false (the default setting), rebooted the server, and now I see 24 LogicalProcessors

[sjesse]

Can you share a screenshot of the entire part to show hyperthreading is active? Also can you check if VMkernel.Boot.hyperthreading is set to true

Enable Hyperthreading

it needs to be on in the bios and here.