Hyper-Threading-# of Logical CPUs-Proc Error

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vmskostoff
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Hyper-Threading-# of Logical CPUs-Proc Error

Post by vmskostoff » Tue Jul 09, 2019 5:11 pm

I received a replacement rx3600 and noticed at the EFI prompt, the # of Logical CPUs was 2 instead of 4 as on my previous rx3600.

I scoured the net and found the following procedure:

https://support.hpe.com/hpsc/doc/public ... -c01060323

After running procedure no luck. Same # of logical CPUs.

I did notice that after running the procedure as follows, the # of Logical CPUs went from 2 to 4.

Shell> cpuconfig
Shell> cpuconfig threads on
Shell> reset

When system comes back up and go back into the shell, # of Logical CPUs is 4. This is in direct conflict with the link above.
The link above indicates that through

Shell> cpuconfig threads off

The # of logical CPUs increases to 4. Confusing.

But now you know.

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martinv
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Re: Hyper-Threading-# of Logical CPUs-Proc Error

Post by martinv » Sat Jul 13, 2019 2:31 am

I think the HP support page has the console screenshots for the two cases swapped. If hyperthreading is turned on, each physical core counts as 2 logical CPUs, so with 2 cores you have 4 logicals CPUs. If hyperthreading is turned off, each physical core counts as 1 logical CPU.
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imiller
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Re: Hyper-Threading-# of Logical CPUs-Proc Error

Post by imiller » Mon Jul 15, 2019 10:54 am

Also note that for most OpenVMS applications running with hyperthreading on will give no performance gain and may giving worse performance
Ian Miller
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