Parallels doesn't trigger turbo boost on i5 8257U (MacBook Pro 13" - 2 TB Ports)

J

JoshMono

Junior Member
Hello there,
I'm running into an issue with Parallels 15. I'm running a Windows Guest and all is working quite well, except for that Parallels isn't triggering my CPU's Turbo Boost feature. My MacBook Pro has an i5 with a base clock of 1.4 GHz, but it can turbo boost all the way up to 3.9 GHz. In MacOS and Windows via bootcamp this works fine, but this functionality doesn't seem to work in Parallels. In Parallels the CPU is always reporting a speed of 1.4 GHz, and this is severely impacting the performance of the virtual machine.
Is there some way to fix this? Is this a planned feature, perhaps?
 
Sorry for bumping my own (yet unmoderated) post, but it doesn't seem like I can edit my post (yet). I wanted to add something to my post:

I've done some fiddling around with the Intel Power Tool and found out that while the Windows Guest in Parallels reports a clock speed of 1.4 GHz the Intel Power Tool in MacOS actually reports that the OS is properly requesting a 3.9 GHz clock from the CPU. I suppose that this means that in actuality the CPU is running at 3.9 GHz and Parallels is properly triggering Turbo Boost, but that this isn't being translated into the guest OS, leading to worse performance.

Is there some way to make the virtualized CPU act more like the host CPU?
 
No.

What I mean is that the host CPU turbo boosts all the way up to 3.9 GHz (also when using the VM), but the virtualized CPU always reports a clock speed of 1.4 GHz and seems to perform like that too (it performs comparable to when I disable Turbo Boost on the host CPU).
 
JoshMono said:
No.

What I mean is that the host CPU turbo boosts all the way up to 3.9 GHz (also when using the VM), but the virtualized CPU always reports a clock speed of 1.4 GHz and seems to perform like that too (it performs comparable to when I disable Turbo Boost on the host CPU).
Click to expand...
When you turn the torbo boosts off, does your vm show the same speed as your Mac shows?
 
I performed some Cinebench benchmarks with Turbo on and off. It looks like I'm going to have to come back on my statements. I have the following results:

With Turbo Boost On:
MacOS Average Frequency: 3.4 GHz (also when running Cinebench in Windows)
Windows reported frequency: 1.4 GHz
Windows VM Cinebench Score: 1211
MacOS Cinebench Score: 1702

With Turbo Boost Off:
MacOS Average Frequency: 1.4 GHz (also when running Cinebench in Windows)
Windows Reported frequency: 1.4 GHz
Windows VM Cinebench Score: 469
MacOS Cinebench Score: 671

In both cases the performance loss in the VM is similar (29% VS 30%) which would indicate that this loss is caused by virtualization; not by the seeming lack of turbo boost.

It looks like the reported (virtual) frequency in Windows is either not accurate or the emulated CPU simply reports a static (virtual) clock frequency even though this is not what the CPU is actually doing. In the end it looks like having Turbo Boost enabled does actually make the host CPU work at higher frequencies even though this is not reported in the virtual machine. So Parallels somehow not triggering Turbo Boost is not true. The host CPU engages Turbo just fine. It just isn't reported in the virtual machine.

In that case I suppose I'm running into a different issue altogether for which I'll do some more research and make an new topic, in case that's necessary.
 
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