Disable Hyper-threading on Azure Instance

The instructions below are a workaround supplied by Azure. We do not know if this is officially supported by MS or if it will change in the future. The instance used was general compute instance Standard D32as V4.

Do the following to disable hyper-threading.

On the Azure instance:

Run the following command:
```
#vi /etc/default/grub
```

In /etc/default/grub, add nosmt to the end of the GRUB_CMDLINE_LINUX entry:

GRUB_CMDLINE_LINUX="console=tty1 console=ttyS0 earlyprintk=ttyS0 rootdelay=300 crashkernel=auto nosmt"

Set boot load kernel configuration by running:

#cp /boot/grub2/grub.cfg  /boot/grub2/grub.cfg_bak   //backup the grub file

#grub2-mkconfig -o /boot/grub2/grub.cfg

Reboot the VM.

Confirm the procedure worked by running:

lscpu

example results:

Before and After of the VM:

Copy

Before:

[root@<machine-IP> ~]# lscpu
                    Architecture:          x86_64
                    CPU op-mode(s):        32-bit, 64-bit
                    Byte Order:            Little Endian
                    CPU(s):                32
                    On-line CPU(s) list:   0-31
                    Thread(s) per core:    2
                    Core(s) per socket:    16
                    Socket(s):             1
                    NUMA node(s):          2
                    Vendor ID:             AuthenticAMD
                CPU family:            25

Copy

After Running the above commands and successful reboot:

[root@<machine-IP> ~]# lscpu
                    Architecture:          x86_64
                    CPU op-mode(s):        32-bit, 64-bit
                    Byte Order:            Little Endian
                    CPU(s):                32
                    On-line CPU(s) list:   0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30
                    Off-line CPU(s) list:  1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31
                    Thread(s) per core:    1
                Core(s) per socket:    16