Info on Hyperthreading

[sbala]

I have 2 dell power edge R620 servers and installed ESXi 5.1 in it. I thought HT would be enabled by default in this server but after installing ESXi i saw it was not enabled. I enabled HT option after installaing the OS but in vSphere client HT option is still disabled. When i checked with Dell they told HT is enabled and there is no issues on hardware side may be you can reinstall ESXi and check, if not you will have to check with VMware support.

Can someone guide me on how to enable the HT?

Thanks

Bala

[LennieDH]

Generally speaking Hyperthreading can be enabled in BIOS.

Usually it's in configuration tab, under CPU there's should be something similar to "Intel hyper-threading technology" which can be set Enabled/Disabled.

Hope this helps,

Regards,

Paolo

[a_p_]

... but in vSphere client HT option is still disabled

Where do you see this? Please check on the hosts's "Summary" tab how many logical CPU's are available.

Btw. besides HT you may also want to ensure "VT-x" as well as "Execute Disable Bit" are both enabled.

André

[Cooldude09]

bala as a best practise by Vmware , keep it disabled.

-AJ

[a_p_]

... as a best practise by Vmware , keep it disabled.

Interesting. Afaik it's the other way around, at least with Nehalem or newer CPUs.

André

[Cooldude09]

Andre, simple reason mentioned by VMware (as i heard in their training - design workshop) was that vmkernel with do all CPU scheduling and enabling HT just adds some overhead and doesn't do any value add to the performance. So all controls to be kept with vmkernel...

[a_p_]

At least according to http://www.vmware.com/pdf/Perf_Best_Practices_vSphere5.0.pdf (page 20 ff) it's recommended to enable Hyper-Threading.

For the best performance we recommend that you enable hyper-threading, ...

André

[sbala]

BIOS settings has been verified on hardware side. All options regarding HT are set and verified by Dell.

[sbala]

Hi Andre,

I have attached snaps of the HT status which is displayed on vSphere client.

[a_p_ · Accepted solution]

According to the Intel web site (http://ark.intel.com/products/64588/Intel-Xeon-Processor-E5-2609-10M-Cache-2_40-GHz-6_40-GTs-Intel-Q...) your CPU does not support HT.

André

[sbala]

Thanks Andre. I was in the impression that HT is supported in this hardware. Even Dell Tech support told me HT is supported in this server. Anyways thanks again.