Which size provides / how to get fastest single thread performance on a Windows Azure VM

Question

Hello,
whatever Azure VM size family i use (tried FXmds, DCv2, FSv2, Dadsv5, etc.), i am not able to get the same single thread performance as a physical i5-12500.

I think that this is due to the hypervisor not allowing the cpu to speed up a single core to it´s max turbo clock speed. Is this correct ?

What i´ve tried:

• Setting power mode to "ultimate performance"
• tried different VMs on a dedicated host (neither using 1 core nor using all cores helps)

Hence, i have two questions:

• is it possible to enable Azure VMs to leverage turbo boost (speed up a single or all cores)?
• if not, which VM Size SKU should i use to get the best single core performance?

Regards,
Holger

Answer 1

Hello @Seitz, Holger

It's possible that the hypervisor is limiting the CPU's ability to reach its maximum turbo clock speed. However, there are a few things you can try to improve single-thread performance on Azure VMs.

First, you can try using a VM size with a higher clock speed. For example, the Fsv2 series has a maximum clock speed of 3.7 GHz, while the M series has a maximum clock speed of 3.5 GHz. You can also try using a VM size with fewer vCPUs, as this can sometimes improve single-thread performance.

Second, you can try disabling hyper-threading on the VM. Hyper-threading can sometimes cause performance issues, especially in applications that are not optimized for it.

Finally, you can try using a custom image with the latest version of the Azure Linux Agent. The latest version of the agent includes performance optimizations that can improve single-thread performance.

Regarding your question about enabling turbo boost, Azure VMs do support turbo boost, but the exact behavior depends on the VM size and the hypervisor. In general, the hypervisor will try to balance performance and stability, so it may not always allow the CPU to reach its maximum turbo clock speed.

I hope this helps! Let me know if you have any other questions.